Protein Tyrosine Phosphatase Receptor Zeta 1 as a Potential Target in Cancer Therapy and Diagnosis.

Protein tyrosine phosphatase receptor zeta 1 (PTPRZ1) is a type V transmembrane tyrosine phosphatase that is highly expressed during embryonic development, while its expression during adulthood is limited. PTPRZ1 is highly detected in the central nervous system, affecting oligodendrocytes' survival and maturation. In gliomas, PTPRZ1 expression is significantly upregulated and is being studied as a potential cancer driver and as a target for therapy. PTPRZ1 expression is also increased in other cancer types, but there are no data on the potential functional significance of this finding. On the other hand, low PTPRZ1 expression seems to be related to a worse prognosis in some cancer types, suggesting that in some cases, it may act as a tumor-suppressor gene. These discrepancies may be due to our limited understanding of PTPRZ1 signaling and tumor microenvironments. In this review, we present evidence on the role of PTPRZ1 in angiogenesis and cancer and discuss the phenomenal differences among the different types of cancer, depending on the regulation of its tyrosine phosphatase activity or ligand binding. Clarifying the involved signaling pathways will lead to its efficient exploitation as a novel therapeutic target or as a biomarker, and the development of proper therapeutic approaches.

Regulation of Cx43 Gap Junction Intercellular Communication by Bruton's Tyrosine Kinase and Interleukin-2-Inducible T-Cell Kinase.

T and B cell receptor signaling involves the activation of Akt, MAPKs, and PKC as well as an increase in intracellular Ca2+ and calmodulin activation. While these coordinate the rapid turnover of gap junctions, also implicated in this process is Src, which is not activated as part of T and B cell receptor signaling. An in vitro kinase screen identified that Bruton's tyrosine kinase (BTK) and interleukin-2-inducible T-cell kinase (ITK) phosphorylate Cx43. Mass spectroscopy revealed that BTK and ITK phosphorylate Cx43 residues Y247, Y265, and Y313, which are identical to the residues phosphorylated by Src. Overexpression of BTK or ITK in the HEK-293T cells led to increased Cx43 tyrosine phosphorylation as well as decreased gap junction intercellular communication (GJIC) and Cx43 membrane localization. In the lymphocytes, activation of the B cell receptor (Daudi cells) or T cell receptor (Jurkat cells) increased the BTK and ITK activity, respectively. While this led to increased tyrosine phosphorylation of Cx43 and decreased GJIC, the cellular localization of Cx43 changed little. We have previously identified that Pyk2 and Tyk2 also phosphorylate Cx43 at residues Y247, Y265, and Y313 with a similar cellular fate to that of Src. With phosphorylation critical to Cx43 assembly and turnover, and kinase expression varying between different cell types, there would be a need for different kinases to achieve the same regulation of Cx43. The work presented herein suggests that in the immune system, ITK and BTK have the capacity for the tyrosine phosphorylation of Cx43 to alter the gap junction function in a similar manner as Pyk2, Tyk2, and Src.

An unanticipated discourse of HB-EGF with VANGL2 signaling during embryo implantation.

Implantation is the first direct encounter between the embryo and uterus during pregnancy, and Hbegf is the earliest known molecular signaling for embryo-uterine crosstalk during implantation. The downstream effectors of heparin-binding EGF (HB-EGF) in implantation remain elusive due to the complexity of EGF receptor family. This study shows that the formation of implantation chamber (crypt) triggered by HB-EGF is disrupted by uterine deletion of Vangl2, a key planar cell polarity component (PCP). We found that HB-EGF binds to ERBB2 and ERBB3 to recruit VANGL2 for tyrosine phosphorylation. Using in vivo models, we show that uterine VAGL2 tyrosine phosphorylation is suppressed in Erbb2/Erbb3 double conditional knockout mice. In this context, severe implantation defects in these mice lend support to the critical role of HB-EGF-ERBB2/3-VANGL2 in establishing a two-way dialogue between the blastocyst and uterus. In addition, the result addresses an outstanding question how VANGL2 is activated during implantation. Taken together, these observations reveal that HB-EGF regulates the implantation process by influencing uterine epithelial cell polarity comprising VANGL2.

Tyrosinase-Catalyzed Peptide Macrocyclization for mRNA Display.

mRNA display of macrocyclic peptides has proven itself to be a powerful technique to discover high-affinity ligands for a protein target. However, only a limited number of cyclization chemistries are known to be compatible with mRNA display. Tyrosinase is a copper-dependent oxidase that oxidizes tyrosine phenol to an electrophilic o-quinone, which is readily attacked by cysteine thiol. Here we show that peptides containing tyrosine and cysteine are rapidly cyclized upon tyrosinase treatment. Characterization of the cyclization reveals it to be widely applicable to multiple macrocycle sizes and scaffolds. We combine tyrosinase-mediated cyclization with mRNA display to discover new macrocyclic ligands targeting melanoma-associated antigen A4 (MAGE-A4). These macrocycles potently inhibit the MAGE-A4 binding axis with nanomolar IC50 values. Importantly, macrocyclic ligands show clear advantage over noncyclized analogues with ∼40-fold or greater decrease in IC50 values.

Impact of Physicochemical Modifications in Casein Promoted by UV-C on the Peptide Profile of Gastric Digestion and the Transepithelial Transport of Peptides.

Caseins are the main proteins in milk, and their structure and spatial conformation are responsible for their slow digestion rate. The release of bioactive and ß-casomorphin peptides from casein digestion may induce allergic responses during consumption. Spectroscopic techniques were used to observe the structural changes in casein conformation induced by Ultraviolet light irradiation (UV-C). Raman spectroscopy results showed more pronounced peaks at 618 and 640 cm-1 for phenylalanine and tyrosine moieties of the photolyzed micellar casein, respectively, suggesting changes in the micelle structure. The decrease in the intensity of Raman signals for tryptophan and tyrosine corroborates to the UV-C-induced modifications of the micelle structure. Particle size distribution showed a decrease in the average micelle size after 15 min of UV-C exposure, while low-temperature, long-time (LTLT) pasteurization led to the formation of large aggregates, as observed by atomic force microscopy. UV-C did not impact the formation or transport of peptides, as observed by using the Caco-2 cell as a model for peptide absorption. However, the absence of the opioid peptide SRYPSY from κ-casein and only 20% of the concentration of opioid peptide RYLGY were noted. This work demonstrated that UV-C can be utilized to induce the physicochemical modification of dairy products, promoting a higher digestion rate and reducing allergenicity.

Comparison of Metabolic Response to Colonic Fermentation in Lean Youth vs Youth With Obesity.

Importance: Pediatric obesity is a growing health care burden. Understanding how the metabolic phenotype of youth with obesity may modify the effect of intestinal fermentation on human metabolism is key to designing early intervention. Objective: To assess whether adiposity and insulin resistance in youth may be associated with colonic fermentation of dietary fibers and its production of acetate, gut-derived hormone secretion, and adipose tissue lipolysis. Design, Setting, and Participants: Cross-sectional study of youths aged 15 to 22 years with body mass index in the 25th to 75th percentile or higher than the 85th percentile for age and sex throughout the New Haven County community in Connecticut. Recruitment, studies, and data collection occurred from June 2018 to September 2021. Youths were assigned to a lean, obese insulin sensitive (OIS), or obese insulin resistant (OIR) group. Data were analyzed from April 2022 to September 2022. Exposure: Participants consumed 20 g of lactulose during a continuous 10-hour sodium d3-acetate intravenous infusion to measure the rate of appearance of acetate in plasma. Main Outcomes and Measures: Plasma was obtained hourly to measure acetate turnover, peptide tyrosine tyrosine (PYY), ghrelin, active glucagon-like peptide 1 (GLP-1), and free fatty acids (FFA). Results: A total of 44 youths participated in the study (median [IQR] age, 17.5 [16.0-19.3] years; 25 [56.8%] were female; 23 [52.3%] were White). Consequent to lactulose ingestion, there was a reduction of plasma FFA, an improvement of adipose tissue insulin sensitivity index, an increase in colonic acetate synthesis, and an anorexigenic response characterized by an increased plasma concentration of PYY and active GLP-1 and a reduction of ghrelin in the subgroups. Compared with the lean and OIS groups, the OIR group showed a less marked median (IQR) rate of acetate appearance (OIR: 2.00 [-0.86 to 2.69] µmol × kg-1 × min-1; lean: 5.69 [3.04 to 9.77] µmol × kg-1 × min-1; lean vs OIR P = .004; OIS: 2.63 [1.22 to 4.52] µmol × kg-1 × min-1; OIS vs OIR P = .09), a blunted median (IQR) improvement of adipose insulin sensitivity index (OIR: 0.043 [ 0.006 to 0.155]; lean: 0.277 [0.220 to 0.446]; lean vs OIR P = .002; OIS: 0.340 [0.048 to 0.491]; OIS vs OIR P = .08), and a reduced median (IQR) PYY response (OIR: 25.4 [14.8 to 36.4] pg/mL; lean: 51.3 [31.6 to 83.3] pg/mL; lean vs OIR P = .002; OIS: 54.3 [39.3 to 77.2] pg/mL; OIS vs OIR P = .011). Conclusions and Relevance: In this cross-sectional study, lean, OIS, and OIR youth demonstrated different associations between colonic fermentation of indigestible dietary carbohydrates and the metabolic response, with OIR youth showing minimal metabolic modifications as compared with the other 2 groups. Trial Registration: ClinicalTrials.gov Identifier: NCT03454828.

Nano-bio interface between As4S4 nanoparticles and albumin influenced by wet stirred media milling.

Arsenic sulfide (As4S4) nanoparticles have been intensively researched as a promising drug in a cancer treatment. For the first time, the interaction between As4S4 and bovine serum albumin has been studied in this paper. Initially, the sorption kinetics of albumin on the surface of nanoparticles was investigated. Subsequently, its structural changes influenced by interaction with the As4S4 nanoparticles during wet stirred media milling were studied in deep. Both the dynamic and static quenching were detected after analyzing the fluorescence quenching spectra. From the synchronous fluorescence spectra it was investigated, that the fluorescence intensity for tyrosine residues decreased by about 55%, and for tryptophan it was about 80%. It indicates the fluorescence from tryptophan is more intense and gets more efficiently quenched than those from tyrosine residues in presence of As4S4, implying that the tryptophan can be closer to the binding site. From the circular dichroisms and FTIR spectra it was observed that conformation of the protein remains almost unchanged. The content of appropriate secondary structures was determined by deconvolution of the absorption peak attributed to the amide I band in FTIR spectra. The preliminary anti-tumor cytotoxic effect of prepared albumin-As4S4 system was also tested on multiple myeloma cell lines.

A Metabolism-Based Interpretable Machine Learning Prediction Model for Diabetic Retinopathy Risk: A Cross-Sectional Study in Chinese Patients with Type 2 Diabetes.

The burden of diabetic retinopathy (DR) is increasing, and the sensitive biomarkers of the disease were not enough. Studies have found that the metabolic profile, such as amino acid (AA) and acylcarnitine (AcylCN), in the early stages of DR patients might have changed, indicating the potential of metabolites to become new biomarkers. We are amid to construct a metabolite-based prediction model for DR risk. This study was conducted on type 2 diabetes (T2D) patients with or without DR. Logistic regression and extreme gradient boosting (XGBoost) prediction models were constructed using the traditional clinical features and the screening features, respectively. Assessing the predictive power of the models in terms of both discrimination and calibration, the optimal model was interpreted using the Shapley Additive exPlanations (SHAP) to quantify the effect of features on prediction. Finally, the XGBoost model incorporating AA and AcylCN variables had the best comprehensive evaluation (ROCAUC = 0.82, PRAUC = 0.44, Brier score = 0.09). C18 : 1OH lower than 0.04 µmol/L, C18 : 1 lower than 0.70 µmol/L, threonine higher than 27.0 µmol/L, and tyrosine lower than 36.0 µmol/L were associated with an increased risk of developing DR. Phenylalanine higher than 52.0 µmol/L was associated with a decreased risk of developing DR. In conclusion, our study mainly used AAs and AcylCNs to construct an interpretable XGBoost model to predict the risk of developing DR in T2D patients which is beneficial in identifying high-risk groups and preventing or delaying the onset of DR. In addition, our study proposed possible risk cut-off values for DR of C18 : 1OH, C18 : 1, threonine, tyrosine, and phenylalanine.

Formation of a Purple Product upon the Reaction of ABTS Radicals with Proteins.

The reaction of the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) free radical (ABTS●) with proteins (bovine serum albumin, blood plasma, egg white, erythrocyte membranes, and Bacto Peptone) leads not only to a reduction of ABTS● but also to the appearance of a purple color (absorption maximum at 550-560 nm). The aim of this study was to characterize the formation and explain the nature of the product responsible for the appearance of this color. The purple color co-precipitated with protein, and was diminished by reducing agents. A similar color was generated by tyrosine upon reaction with ABTS●. The most feasible explanation for the color formation is the addiction of ABTS● to proteins' tyrosine residues. The product formation was decreased by nitration of the bovine serum albumin (BSA) tyrosine residues. The formation of the purple product of tyrosine was optimal at pH 6.5. A decrease in pH induced a bathochromic shift of the spectra of the product. The product was not a free radical, as demonstrated by electrom paramagnetic resonance (EPR) spectroscopy. Another byproduct of the reaction of ABTS● with tyrosine and proteins was dityrosine. These byproducts can contribute to the non-stoichiometry of the antioxidant assays with ABTS●. The formation of the purple ABTS adduct may be a useful index of radical addition reactions of protein tyrosine residues.

A voltammetric sensor based on a reduced graphene oxide/ß-cyclodextrin/silver nanoparticle/polyoxometalate nanocomposite for detecting uric acid and tyrosine.

In the present work, an electrochemical sensor based on reduced graphene oxide/ß-cyclodextrin/silver nanoparticle/polyoxometalate (RGO-CD-AgNP-POM) was developed for the simultaneous detection of uric acid (UA) and L-tyrosine (L-Tyr). First, an RGO-CD-AgNP-POM nanocomposite was synthesized via a simple photoreduction method and characterized by transmission electron microscopy (TEM), energy dispersive X-ray imaging (EDS), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). As an electrode material, RGO-CD-AgNP-POM showed wide linear ranges (0.5-500 µM for UA, and 1-400 µM for L-Tyr) and relatively low detection limits (0.11 µM for UA, and 0.23 µM for L-Tyr). In addition, the combination of supramolecular recognition from CD and excellent electrochemical performances from RGO, AgNPs and POM was expected to enhance the sensing performances toward UA and L-Tyr in real samples with favorable recovery ranges (99%-104%). This nanocomposite provides a new platform for developing the family of electrode materials.

Predictive data-driven modeling of C-terminal tyrosine function in the EGFR signaling network.

The epidermal growth factor receptor (EGFR) has been studied extensively because of its critical role in cellular signaling and association with disease. Previous models have elucidated interactions between EGFR and downstream adaptor proteins or showed phenotypes affected by EGFR. However, the link between specific EGFR phosphorylation sites and phenotypic outcomes is still poorly understood. Here, we employed a suite of isogenic cell lines expressing site-specific mutations at each of the EGFR C-terminal phosphorylation sites to interrogate their role in the signaling network and cell biological response to stimulation. Our results demonstrate the resilience of the EGFR network, which was largely similar even in the context of multiple Y-to-F mutations in the EGFR C-terminal tail, while also revealing nodes in the network that have not previously been linked to EGFR signaling. Our data-driven model highlights the signaling network nodes associated with distinct EGF-driven cell responses, including migration, proliferation, and receptor trafficking. Application of this same approach to less-studied RTKs should provide a plethora of novel associations that should lead to an improved understanding of these signaling networks.

Filter blot method: A simple method for measuring 3-nitrotyrosine in proteins of atmospheric particulate matter.

Air pollutants, such as nitrogen dioxide (NO2), ozone (O3), and particulate matter (PM), have been epidemiologically reported to contribute to the onset and exacerbation of asthma. We have previously shown that several proteins in atmospheric PM are allergenic in mouse asthma models and that these proteins are nitrated by atmospheric NO2 and O3 in chemical reactions. Based on these results, the amount of 3-nitrotyrosine (3-NT) in atmospheric PM could be an air pollution marker integrating NO2, O3, and PM. We established a method to measure 3-NT by high-performance liquid chromatography electrochemical detection (HPLC-ECD). Although this method is accurate, it requires a filter treatment process, which is time-consuming and costly for an environmental monitoring tool, in which many samples are measured simultaneously. Therefore, in this study, we investigated a simple immunoblotting method in which atmospheric PM proteins were directly transferred to a polyvinylidene fluoride (PVDF) membrane and measured using an anti-3-NT antibody (the filter blot method). The 3-NT value obtained from this method was significantly correlated (r = 0.809, p < 0.001) with that of the HPLC-ECD method, with a detection power of 0.1 µg/mL for tyrosine nitrated bovine serum albumin equivalents. Multiple regression analysis using the filter blot method showed that the amount of 3-NT in atmospheric PM was significantly associated with the published environmental measurements of O3 and PM in the region. Therefore, the filter blot method may be useful for the environmental monitoring of 3-NT in atmospheric PM.

Standardized ileal digestibility of amino acids in cottonseed meal fed to pregnant and non-pregnant sows.

This study determined the apparent ileal digestibility (AID) and standard ileal digestibility (SID) of crude protein (CP) and amino acids (AA) of six cottonseed meal (CSM) samples in pregnant and non-pregnant sows. Two CSM samples were processed by expelling with a CP level of 40.67% (ECSM41) and 44.64% (ECSM45), and four samples were processed by solvent-extracted which contained graded CP levels of 45% (SECSM45), 51.16% (SECSM51), 56.44% (SECSM56), and 59.63% (SECSM60). Landrace ×Yorkshire third parity sows, 7 at gestation and 14 non-pregnant, were fitted with T-cannula in the distal ileum. Pregnant sows were allotted to a 7 × 6 Latin square design with a cornstarch-based nitrogen-free (NF) diet and the six CSM diets, and non-pregnant sows were allotted to a replicated 7 × 3 Latin square design with seven diets and three periods, respectively, resulting in a total of six replicates per treatment. All experimental sows were fed 3.0 kg/d of the experimental diets. The AID of CP in ECSM41 (75.58%) was lower than in SECSM51 (80.42%), SECSM56 (80.50%), and SECSM60 (82.44%) diets for pregnant sows (P < 0.05). The AID of CP in ECSM41 (77.88%) was significantly lower than in SECSM60 (81.87%) diets for non-pregnant sows (P < 0.05). The physiological phase did not affect the AID of CP (P > 0.05). The SID of CP was affected by diets for both pregnant (P < 0.01) and non-pregnant sows (P = 0.06). The physiological phase also affected the SID of CP (P < 0.01). The AID of histidine, leucine, methionine, threonine, and tryptophan significantly differed between different CSM samples in both pregnant (P < 0.05) and non-pregnant sows (P < 0.05). The AID of dispensable AA aspartic acid, cysteine, glutamic acid, serine, and tyrosine differed between different CSM samples of both pregnant (P < 0.05) and non-pregnant sows (P < 0.05). For pregnant sows, the indispensable AA cysteine, glycine, proline, and tyrosine had significantly different SID between different groups (P < 0.05). For non-pregnant sows, the SID of arginine, lysine, methionine, threonine, aspartic acid, cysteine, and serine had different values among different diets (P < 0.05). In conclusion, the current study presented that the ileal AA digestibility of CSM fed to pregnant and non-pregnant sows increased with the decreased of fiber content, and the current findings can contribute to a precise formulation of diets for sows using CSM.

As a protein-rich cottonseed byproduct, cottonseed meal (CSM) is considered a vegetable protein source that can substitute soybean meal in the feed of livestock animals. However, the presence of free gossypol and high fiber levels in CSM have been limiting factors for its use in growing and finishing pigs, yet its nutritive value is still uncertain for sows. There is a lack of standard ileal digestibility (SID) of amino acids (AA) for plant proteins because fitting a T-cannula in the distal ileum is difficult. Therefore, this study evaluated the apparent ileal digestibility and SID of 18 AA of CSM in sows at two physiological stages (gestation and non-pregnancy). We found that CSM with different chemical compositions impacted the SID of AA when fed to pregnant and non-pregnant sows. Additionally, the physiological stage of the sow has a substantial impact on the SID of some AA. The current findings of this study provided a basis for the precise formulation of sow diets with CSM.

Tyrosine-derived polymeric surfactant nanospheres insert cholesterol in cell membranes.

HYPOTHESIS: The design of biodegradable tyrosine-derived polymeric surfactants (TyPS) through the use of calculated thermodynamic parameters could lead to phospholipid membrane surface modifiers capable of controlling cellular properties such as viability. Delivery of cholesterol by TyPS nanospheres into membrane phospholipid domains could provide further controlled modulation of membrane physical and biological properties. EXPERIMENT: Calculated Hansen solubility parameters (∂T) and hydrophile:lipophile balances (HLB) were applied to design and synthesize a small family of diblock and triblock TyPS with different hydrophobic blocks and PEG hydrophilic blocks. Self-assembled TyPS/cholesterol nanospheres were prepared in aqueous media via co-precipitation. Cholesterol loading and Langmuir film balance surface pressures of phospholipid monolayers were obtained. TyPS and TyPS/cholesterol nanosphere effects on human dermal cell viability were evaluated by cell culture using poly(ethylene glycol) (PEG) and Poloxamer 188 as controls. FINDINGS: Stable TyPS nanospheres incorporated between 1% and 5% cholesterol. Triblock TyPS formed nanosphere with dimensions significantly smaller than diblock TyPS nanospheres. In accord calculated thermodynamic parameters, cholesterol binding increased with increasing TyPS hydrophobicity. TyPS inserted into phospholipid monolayer films in a manner consistent with their thermodynamic properties and TyPS/cholesterol nanospheres delivered cholesterol into the films. Triblock TyPS/cholesterol nanospheres increased human dermal cell viability, which was indicative of potentially beneficial TyPS effects on cell membrane surface properties.

Membrane Protein Binding Interactions Studied in Live Cells via Diethylpyrocarbonate Covalent Labeling Mass Spectrometry.

Membrane proteins are vital in the human proteome for their cellular functions and make up a majority of drug targets in the U.S. However, characterizing their higher-order structures and interactions remains challenging. Most often membrane proteins are studied in artificial membranes, but such artificial systems do not fully account for the diversity of components present in cell membranes. In this study, we demonstrate that diethylpyrocarbonate (DEPC) covalent labeling mass spectrometry can provide binding site information for membrane proteins in living cells using membrane-bound tumor necrosis factor α (mTNFα) as a model system. Using three therapeutic monoclonal antibodies that bind TNFα, our results show that residues that are buried in the epitope upon antibody binding generally decrease in DEPC labeling extent. Additionally, serine, threonine, and tyrosine residues on the periphery of the epitope increase in labeling upon antibody binding because of a more hydrophobic microenvironment that is created. We also observe changes in labeling away from the epitope, indicating changes to the packing of the mTNFα homotrimer, compaction of the mTNFα trimer against the cell membrane, and/or previously uncharacterized allosteric changes upon antibody binding. Overall, DEPC-based covalent labeling mass spectrometry offers an effective means of characterizing structure and interactions of membrane proteins in living cells.

Chemoselective, Oxidation-Induced Macrocyclization of Tyrosine-Containing Peptides.

Inspired by nature's wide range of oxidation-induced modifications to install cross-links and cycles at tyrosine (Tyr) and other phenol-containing residue side chains, we report a Tyr-selective strategy for the preparation of Tyr-linked cyclic peptides. This approach leverages N4-substituted 1,2,4-triazoline-3,5-diones (TADs) as azo electrophiles that react chemoselectively with the phenolic side chain of Tyr residues to form stable C-N1-linked cyclic peptides. In the developed method, a precursor 1,2,4-triazolidine-3,5-dione moiety, also known as urazole, is readily constructed at any free amine revealed on a solid-supported peptide. Once prepared, the N4-substituted urazole peptide is selectively oxidized using mild, peptide-compatible conditions to generate an electrophilic N4-substituted TAD peptide intermediate that reacts selectively under aqueous conditions with internal and terminal Tyr residues to furnish Tyr-linked cyclic peptides. The approach demonstrates good tolerance of native residue side chains and enables access to cyclic peptides ranging from 3- to 11-residues in size (16- to 38-atom-containing cycles). The identity of the installed Tyr-linkage, a stable covalent C-N1 bond, was characterized using NMR spectroscopy. Finally, we applied the developed method to prepare biologically active Tyr-linked cyclic peptides bearing the integrin-binding RGDf epitope.

Spectroscopic Investigation of the Metal Coordination of the Aromatic Amino Acids with Zinc and Cadmium.

The aromatic amino acids (AAA), phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp), were cationized with ZnCl+ and CdCl+, and the complexes were evaluated using infrared multiple photon dissociation (IRMPD) action spectroscopy. Specifically, the ZnCl+(Phe), CdCl+(Phe), ZnCl+(Tyr), CdCl+(Tyr), and ZnCl+(Trp) species were examined because the CdCl+(Trp) IRMPD spectrum is available in the literature. Several low-energy conformers for all complexes were found using quantum chemical calculations, and their simulated vibrational spectra were compared to the experimental IRMPD spectra to identify dominant isomers formed. In the case of MCl+(Phe) and MCl+(Tyr), these comparisons indicated the dominant binding motif is a tridentate structure, where the metal atom coordinates with the backbone amino nitrogen and carbonyl oxygen, as well as the aryl ring. These observations are consistent with the predicted ground states at the B3LYP, B3P86, B3LYP-GD3BJ, and MP2 levels of theory. For the ZnCl+(Trp) system, the experimental spectrum indicates a similar binding motif, with the zinc atom coordinating with the backbone nitrogen and carbonyl oxygen and either the pyrrole ring or the benzene ring of the indole side chain. These observations are consistent with the predicted low-lying conformers identified by the aforementioned levels of theory, with the B3LYP and B3P86 levels predicting the metal-pyrrole ring interaction is more favorable than the metal-benzene ring interactions and the opposite at the B3LYP-GD3BJ and MP2 levels.

A fluorophore anchored MOF for fast and sensitive sensing of Cu(II) and 3-nitrotyrosine in a physiological medium.

We report the solvothermal synthesis of a dansyl anchored hafnium based fluorescent metal-organic framework (MOF) having the formula [Hf6O4(OH)4(L)6]·H2O·6DMF (H2L = 2-((5-(dimethylamino)naphthalene)-1-sulfonamido)terephthalic acid). The synthesized material showed high fluorescence emission properties as well as high thermal (stable up to 330 °C) and chemical stability. It also exhibited a wide range of pH tolerance as well as a high BET surface area of 703 m2 g-1. The activated MOF showed ultra-fast (detection time < 10 s) and ultra-sensitive sensing properties towards Cu(II) and the biologically important biomarker 3-nitrotyrosine (3-NTyr) in a HEPES medium at a physiological pH of 7.4. Along with high selectivity, very low detection limits of 229 nM and 539 nM were obtained for Cu(II) and 3-NTyr respectively. Furthermore, this probe was utilised for the detection and quantification of Cu(II) and 3-NTyr in biosamples (urine and serum) with very low RSD values (2.3-4.8%). Additionally, this probe was employed to detect the presence of Cu(II) as a pollutant in various environmental water samples. Furthermore, for rapid economic detection of Cu(II), a MOF coated fluorescent paper strip was demonstrated. Thorough mechanistic investigations displayed that a complexometric interaction between Cu(II) and the probe is the main reason for the quenching of fluorescence intensity. This proposed mechanism was well supported by experimental evidence. On the other hand, the FRET mechanism is proposed based on the experimental observations for dynamic quenching of the fluorescence intensity of the probe in the presence of 3-NTyr.

Higher dietary intake of aromatic amino acids was associated with lower risk of cardiovascular disease mortality in adult participants in NHANES III.

Little is known about the associations between dietary aromatic amino acids (AAAs) intake and mortality from all causes and cardiovascular disease (CVD). Accordingly, we evaluated these associations in the adult population of the United States using data from the Third National Health and Nutrition Examination Survey. This was a cohort study. Dietary intake of AAAs (tyrosine, phenylalanine, and tryptophan) was determined from the total nutrient intake document. We hypothesized that higher dietary AAA intake would lower all-cause and CVD mortality in adults in the United States. First, we categorized participants into quintiles based on their dietary intakes of total AAAs, tyrosine, phenylalanine, and tryptophan. Then, we established 4 Cox proportional-hazards models (models 1-4) and calculated hazard ratios and 95% confidence intervals to estimate the associations between dietary intakes of total AAAs, tyrosine, phenylalanine, and tryptophan and all-cause and CVD mortality. Mortality status was primarily obtained from files linked to the National Death Index records up to December 31, 2015. After multivariate adjustment, the hazard ratios (95% confidence intervals) of CVD mortality in the highest quintiles of dietary total AAAs, tyrosine, phenylalanine, and tryptophan intake (reference: the lowest quintiles) were 0.66 (0.52-0.84), 0.65 (0.51-0.83), 0.66 (0.52-0.85) and 0.64 (0.50-0.82), respectively. In a nationally representative cohort, higher dietary intakes of total AAA and the 3 individual AAAs were independently associated with a lower risk of CVD mortality, and these associations were stronger in non-Hispanic White people than in other people.

Antibodies Directed Against GalNAc- and GlcNAc-O-Tyrosine Posttranslational Modifications - a New Tool for Glycoproteomic Detection.

In the last decade, it was discovered that protein mucin-type O-glycosylation and O-GlcNAcylation modify Tyr residues besides the well explored Thr and Ser amino acids. Several glycoproteomic studies have identified α-GalNAc-O-Tyr modifications, and studies propose that ß-GlcNAc-O-Tyr also exists as a new group of posttranslational modifications (PTMs). Specific bacterial toxins have further been identified to modify host GTPases with α-GlcNAc-O-Tyr to promote bacterial virulence. Despite being identified on numerous proteins, the biological roles, biosynthesis and expression of GalNAc- and GlcNAc-O-Tyr modifications are poorly understood. A major obstacle is the lack of tools to specifically detect and identify proteins containing these modifications. With this in mind, we prepared vaccine constructs and raised antibodies to enable selective detection of proteins carrying these new PTMs. The obtained polyclonal antibody sera were evaluated using ELISA and glycopeptide microarrays and were found to be highly selective for GlcNAc- and GalNAc-O-Tyr glycopeptides over the corresponding Ser- and Thr-modifications. For microarray analysis, synthetic GlcNAc- and GalNAc-O-Tyr Fmoc-amino acids were prepared and applied in Fmoc-SPPS to obtain an extensive O-glycopeptide library. After affinity purification, the antibodies were applied in western blot analysis and showed specific detection of α-GlcNAc-O-Tyr modified RhoA GTPase.