Expression, Purification, and Determination of Sensitivity to Calcium Ions of Ctenophore Photoproteins.

Light-sensitive Ca2+-regulated photoproteins of ctenophores are single-chain polypeptide proteins of 206-208 amino acids in length comprising three canonical EF-hand Ca2+-binding sites, each of 12 contiguous residues. These photoproteins are a stable complex of apoprotein and 2-hydroperoxy adduct of coelenterazine. Addition of calcium ions to photoprotein is only required to trigger bright bioluminescence. However, in contrast to the related Ca2+-regulated photoproteins of jellyfish their capacity to bioluminescence disappears on exposure to light over the entire absorption spectral range of ctenophore photoproteins. Here, we describe protocols for expression of gene encoding ctenophore photoprotein in Escherichia coli cells, obtaining of the recombinant apoprotein of high purity and its conversion into active photoprotein with synthetic coelenterazine as well as determination of its sensitivity to calcium ions using light-sensitive Ca2+-regulated photoprotein berovin from ctenophore Beroe abyssicola as an illustrative case.

Engineered biosensors for the quorum sensing molecule 3,5-dimethyl-pyrazine-2-ol (DPO) reveal its presence in humans, animals, and bacterial species beyond Vibrio cholerae.

A biosensor was engineered to enable the study of the novel quorum sensing molecule (QSM), 3,5-dimethylpyrazin-2-ol (DPO), employed by Vibrio cholerae to regulate biofilm formation and virulence factor production. Investigations into bacterial quorum sensing (QS), a form of communication based on the production and detection of QSMs to coordinate gene expression in a population dependent manner, offer a unique window to study the molecular underpinnings of microbial behavior and host interactions. Herein, we report the construction of an engineered microbial whole-cell bioluminescent biosensing system that incorporates the recognition of the VqmA regulatory protein of Vibrio cholerae with the bioluminescent reporting signal of luciferase for the selective, sensitive, stable, and reproducible detection of DPO in a variety of samples. Importantly, using our newly developed biosensor our studies demonstrate the detection of DPO in rodent and human samples. Employing our developed biosensor should help enable elucidation of microbial behavior at the molecular level and its impact in health and disease.

Screening and identification of high yield tetramethylpyrazine strains in Nongxiangxing liquor Daqu and study on the mechanism of tetramethylpyrazine production.

BACKGROUND: There are few reports on the breeding of high-yielding tetramethylpyrazine (TTMP) strains in strong-flavor Daqu. In addition, studies on the mechanism of TTMP production in strains are mostly based on common physiological and biochemical indicators, and there is no report on RNA level. Therefore, in this study, a strain with high production of TTMP was screened out from strong-flavor liquor, and transcriptome sequencing analysis was performed to analyze its key metabolic pathways and key genes, and to infer the mechanism of TTMP production in the strain. RESULTS: In this study, a strain with a high yield of tetramethylpyrazine (TTMP) was screened out, and the yield was 29.83 µg mL-1 . The identified strain was Bacillus velezensis, which could increase the content of TTMP in liquor by about 88%. After transcriptome sequencing, a total of 1851 differentially expressed genes were screened, including 1055 up-regulated genes and 796 down-regulated genes. Three pathways related to the production of TTMP were identified by gene ontology (GO) annotation and COG annotation, including carbohydrate metabolism, cell movement and amino acid metabolism. The key genes of TTMP were analyzed, and the factors that might regulate the production of TTMP, such as the transfer of uracil phosphate ribose and glycosyltransferase, were obtained. CONCLUSIONS: A strain of B. velezensis with high TTMP production was screened and identified in strong-flavor Daqu for the first time. The yield of TTMP was 29.83 µg mL-1 , which increased the TTMP content in liquor by 88%. The key metabolic pathways of TTMP production in the strain were obtained: carbohydrate metabolism, cell movement and amino acid metabolism, and the key regulatory genes of each pathway were found, which complemented the gap in gene level in the production regulation of the strain, and provided a theoretical basis for the subsequent study of TTMP in liquor. © 2023 Society of Chemical Industry.

Comparison of nutritional value, bioactivity, and volatile compounds of soybean meal-corn bran mixed substrates fermented by different microorganisms.

To evaluate the impact of fermentation with different microorganisms on the nutritional quality and bioactivity of soybean meal-corn bran mixed substrates (MS), five lactic acid bacteria (LAB) strains, two Bacillus, and two yeast strains with excellent probiotics were selected for solid-state fermentation of soybean meal and corn bran MS. The fermented mixed substrate (FMS) inoculated with Lacticaseibacillus casei, Lactobacillus fermentum, Lactiplantibacillus plantarum, and Lactobacillus acidophilus presents lower risk of infection with pathogenic bacteria, probably due to their low pH and high lactate content. Compared to the FMS with LAB and yeast, Bacillus subtilis and B. pumilus showed significant improvements in nutritional quality and bioactivity, including TCA-SP, small peptide, free amino acids, total phenol, and protein digestibility. More than 300 volatile compounds were identified in FMS, including alcohols, ketones, aldehydes, esters, acids, ethers, furans, pyrazines, benzene, phenols, amines, alkanes, and others. FMS with Bacillus was characterized as containing a greater number of compounds such as ketones, aldehydes, and pyrazines. This study showed that microbial fermented feeds differed with various microorganism, and fermentation was an effective way to improve the quality of soybean meal-corn bran mixed feeds. This study might be the basis for excellent strains screening for multi-microbial combined fermentation in the future.

Aspergillus ochraceus: Metabolites, Bioactivities, Biosynthesis, and Biotechnological Potential.

Fungus continues to attract great attention as a promising pool of biometabolites. Aspergillus ochraceus Wilh (Aspergillaceae) has established its capacity to biosynthesize a myriad of metabolites belonging to different chemical classes, such as isocoumarins, pyrazines, sterols, indole alkaloids, diketopiperazines, polyketides, peptides, quinones, polyketides, and sesquiterpenoids, revealing various bioactivities that are antimicrobial, cytotoxic, antiviral, anti-inflammatory, insecticidal, and neuroprotective. Additionally, A. ochraceus produces a variety of enzymes that could have variable industrial and biotechnological applications. From 1965 until June 2022, 165 metabolites were reported from A. ochraceus isolated from different sources. In this review, the formerly separated metabolites from A. ochraceus, including their bioactivities and biosynthesis, in addition, the industrial and biotechnological potential of A. ochraceus are highlighted.

Conversion of oxadiazolo[3,4-b]pyrazines to imidazo[4,5-b]pyrazines via a tandem reduction-cyclization sequence generates new mitochondrial uncouplers.

We report new mitochondrial uncouplers derived from the conversion of [1,2,5]oxadiazolo[3,4-b]pyrazines to 1H-imidazo[4,5-b]pyrazines. The in situ Fe-mediated reduction of the oxadiazole fragment followed by cyclization gave access to imidazopyrazines in moderate to good yields. A selection of orthoesters also allowed functionalization on the 2-position of the imidazole ring. This method afforded a variety of imidazopyrazine derivatives with varying substitution on the 2, 5 and 6 positions. Our studies suggest that both a 2-trifluoromethyl group and N-methylation are crucial for mitochondrial uncoupling capacity.

Enzymatic conversion of dehydrocoelenterazine to coelenterazine using FMN-bound flavin reductase of NAD(P)H:FMN oxidoreductase.

Coelenterazine (CTZ) is known as luciferin (a substrate) for the luminescence reaction with luciferase (an enzyme) in marine organisms and is unstable in aqueous solutions. The dehydrogenated form of CTZ (dehydrocoelenterazine, dCTZ) is stable and thought to be a storage form of CTZ and a recycling intermediate from the condensation reaction of coelenteramine and 4-hydroxyphenylpyruvic acid to CTZ. In this study, the enzymatic conversion of dCTZ to CTZ was successfully achieved using NAD(P)H:FMN oxidoreductase from the bioluminescent bacterium Vibrio fischeri ATCC 7744 (FRase) in the presence of NADH (the FRase-NADH reaction). CTZ reduced from dCTZ in the FRase-NADH reaction was identified by HPLC and LC/ESI-TOF-MS analyses. Thus, dCTZ can be enzymatically converted to CTZ in vitro. Furthermore, the concentration of dCTZ could be determined by the luminescence activity using the CTZ-utilizing luciferases (Gaussia luciferase or Renilla luciferase) coupled with the FRase-NADH reaction.

Tetramethylpyrazine alleviates endoplasmic reticulum stress­activated apoptosis and related inflammation in chondrocytes.

Excessive apoptosis of chondrocytes and degradation of the extracellular matrix (ECM) contribute to the typical pathological characteristics of osteoarthritis (OA). Various studies have reported that tetramethylpyrazine (TMP) protects against multiple disorders by inhibiting inflammation and oxidative stress. The present study investigated the effects of TMP on chondrocytes and evaluated the associated mechanisms. To determine the effect of TMP on OA and the underlying mechanisms, chondrocytes were incubated with TMP and IL­1ß or thapsigargin (TG) Western blotting assays were performed to examine the expression levels of endoplasmic reticulum (ER) stress proteins, and TUNEL staining, fluorescence immunostaining and reverse transcription­quantitative PCR were used to determine the apoptosis levels, and catabolic and inflammatory factors. It was found that TMP protected chondrocytes by suppressing IL­1ß­induced expression of glucose­regulated protein 78 (GRP78) and CHOP (an apoptotic protein). TMP regulated the TG­mediated upregulated expression of GRP78 and CHOP in the chondrocytes of rats, as well as markedly suppressed levels of ER stress­triggered inflammatory cytokines (TNF­α and IL­6). Furthermore, TMP modulated TG­induced changes in ECM catabolic metabolism in rat chondrocytes. Collectively, TMP alleviated ER­stress­activated apoptosis and related inflammation in chondrocytes, indicating that it has therapeutic potential for the treatment of OA.

Potential application of lactic acid bacteria in the biopreservation of red grape from mycotoxigenic fungi.

BACKGROUND: Filamentous fungi are the main contamination agent in the viticultural sector. Use of synthetic fungicides is the regular answer to these contaminations. Nevertheless, because of several problems associated with the use of synthetic compounds, the industry demands new and safer methods. In the present work, the biopreservation potential of four lactic acid bacteria (LAB) strains was studied against the principal grape contaminant fungi. RESULTS: Agar diffusion test evidenced that all four culture-free supernatant (CFS) had antifungal properties against all tested fungi. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) test values evidenced that media fermented by the Lactobacillus plantarum E3 and Lactobacillus plantarum E4 strains showed the highest antifungal activity, resulting in an MFC from 6.3 to 100 g L-1 . Analysis of CFS evidenced the presence of different antifungal compounds, such as lactic acid, phenyllactic acid and pyrazines. In tests on red grapes, an average reduction of 1.32 log10 of the spores per gram of fruit was achieved by all CFS in grapes inoculated with Aspergillus ochraceus and by 0.94 log10 for L. plantarum E3 CFS against Botrytis cinerea. CONCLUSION: The antifungal activity of the fermented CFS by L. plantarum E3 reduced the growth of B. cinerea and A. ochraceus in grapes, which are the main contaminant and main producer of ochratoxin A in these crops, respectively. Therefore, based on the results obtained in this work, use of the strain L. plantarum E3 could be an interesting option for the biopreservation of grapes. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of ad libitum Free-Choice Access to Freshly Squeezed Domestic White Asparagus Juice on Intestinal Microbiota Composition and Universal Bio-Markers of Immuno-Metabolic Homeostasis and General Health in Middle-Aged Female and Male C57BL/6 Mice.

BACKGROUND: Asparagus contains different bioactive and volatile components including pyrazines, sulphur-containing compounds, and polyphenols. Asparagus juice is a new low-calorie LAB-containing natural juice product, the usage of which is expanding. Pyrazines and sulphur-containing compounds are degraded by bacteria on one hand, but on the other hand, dietary polyphenols prevent human colorectal diseases as modulators of the composition and/or activity of gut microbiota. However, the utility of these asparagus compounds for reversal of age-associated microbial dysbiosis and the immunometabolic disorders that dysbiosis incites body inflammatory reactions was not much explored so far. Hence, using middle-aged mice, we conducted the current study to verify the effect of freshly squeezed domestic white asparagus juice on the biomarkers reflecting immuno-metabolic pathways linking age-related dysbiosis and metabolic events. MATERIALS AND METHODS: Thirty-two conventional Harlan Laboratories C57BL/6 mice aged between 11-12 months were randomly divided into two groups (n=16). Mice in control group 1 received sterile tap water. Animals in group 2 had 60 days ad libitum free-choice access to sterile tap water supplemented with 5% (v/v) freshly squeezed domestic white asparagus juice. Clinical signs of general health, hydration, and inflammation were monitored daily. Caecal content samples were analysed by qPCR for microbial composition. Histology of relevant organs was carried out on day 60 after sacrificing the mice. Universal markers of metabolic- and liver function were determined in serum samples. Caecal SCFAs contents were measured using HPLC. RESULTS: Overall, no significant differences in general health or clinical signs of inflammation between the two groups were observed. The liver to body weight ratio in asparagus juice-drank mice was lowered. The qPCR quantification showed that asparagus juice significantly decreased the caecal Clostridium coccoides group while causing an enhancement in Clostridium leptum, Firmicutes, and bifidobacterial groups as well as total caecal bacterial count. Asparagus juice significantly elevated the caecal contents of SCFAs. Enhanced SCFAs (acetate, butyrate, and propionate) in mice receiving asparagus juice, however, did coincide with altered lipid levels in plasma or changes in the abundance of relevant bacteria for acetate-, butyrate-, and propionate production. DISCUSSION: To the best of our knowledge, this is the first study aiming at evaluating the effect of freshly squeezed German domestic white asparagus juice on universal markers of metabolic- and liver function in middle- aged mice and the role of gut microbiota in this regard. The effectiveness of asparagus juice to improve metabolism in middle-aged mice was associated with alterations in intestinal microbiota but maybe also due to uptake of higher amounts of SCFAs. CONCLUSION: Hence, the key signal pathways corresponding to improved immune-metabolic homeostasis will be an important research scheme in the future.

Comparative assessment of favipiravir and remdesivir against human coronavirus NL63 in molecular docking and cell culture models.

Human coronavirus NL63 (HCoV-NL63) mainly affects young children and immunocompromised patients, causing morbidity and mortality in a subset of patients. Since no specific treatment is available, this study aims to explore the anti-SARS-CoV-2 agents including favipiravir and remdesivir for treating HCoV-NL63 infection. We first successfully modelled the 3D structure of HCoV-NL63 RNA-dependent RNA polymerase (RdRp) based on the experimentally solved SARS-CoV-2 RdRp structure. Molecular docking indicated that favipiravir has similar binding affinities to SARS-CoV-2 and HCoV-NL63 RdRp with LibDock scores of 75 and 74, respectively. The LibDock scores of remdesivir to SARS-CoV-2 and HCoV-NL63 were 135 and 151, suggesting that remdesivir may have a higher affinity to HCoV-NL63 compared to SARS-CoV-2 RdRp. In cell culture models infected with HCoV-NL63, both favipiravir and remdesivir significantly inhibited viral replication and production of infectious viruses. Overall, remdesivir compared to favipiravir is more potent in inhibiting HCoV-NL63 in cell culture. Importantly, there is no evidence of resistance development upon long-term exposure to remdesivir. Furthermore, combining favipiravir or remdesivir with the clinically used antiviral cytokine interferon-alpha resulted in synergistic effects. These findings provided a proof-of-concept that anti-SARS-CoV-2 drugs, in particular remdesivir, have the potential to be repurposed for treating HCoV-NL63 infection.

Effect of drug metabolism in the treatment of SARS-CoV-2 from an entirely computational perspective.

Understanding the effects of metabolism on the rational design of novel and more effective drugs is still a considerable challenge. To the best of our knowledge, there are no entirely computational strategies that make it possible to predict these effects. From this perspective, the development of such methodologies could contribute to significantly reduce the side effects of medicines, leading to the emergence of more effective and safer drugs. Thereby, in this study, our strategy is based on simulating the electron ionization mass spectrometry (EI-MS) fragmentation of the drug molecules and combined with molecular docking and ADMET models in two different situations. In the first model, the drug is docked without considering the possible metabolic effects. In the second model, each of the intermediates from the EI-MS results is docked, and metabolism occurs before the drug accesses the biological target. As a proof of concept, in this work, we investigate the main antiviral drugs used in clinical research to treat COVID-19. As a result, our strategy made it possible to assess the biological activity and toxicity of all potential by-products. We believed that our findings provide new chemical insights that can benefit the rational development of novel drugs in the future.

Prevalence and Management of Alkyl-Methoxypyrazines in a Changing Climate: Viticultural and Oenological Considerations.

Alkyl-methoxypyrazines are an important class of odor-active molecules that contribute green, 'unripe' characters to wine and are considered undesirable in most wine styles. They are naturally occurring grape metabolites in many cultivars, but can also be derived from some Coccinellidae species when these 'ladybugs' are inadvertently introduced into the must during harvesting operations. The projected impacts of climate change are discussed, and we conclude that these include an altered alkyl-methoxypyrazine composition in grapes and wines in many wine regions. Thus, a careful consideration of how to manage them in both the vineyard and winery is important and timely. This review brings together the relevant literatures on viticultural and oenological interventions aimed at mitigating alkyl-methoxypyrazine loads, and makes recommendations on their management with an aim to maintaining wine quality under a changing and challenging climate.

Etmopterus lantern sharks use coelenterazine as the substrate for their luciferin-luciferase bioluminescence system.

The lantern shark genus Etmopterus contains approximately 40 species of deep-sea bioluminescent cartilaginous fishes. They emit blue light mainly from the ventral body surface. The biological functions of this bioluminescence have been discussed based on the luminescence patterns, but the bioluminescence mechanism remains uncertain. In this study, we detected both coelenterazine and coelenterazine-dependent luciferase activity in the ventral photophore tissue of Etmopterus molleri. The results suggested that bioluminescence in lantern sharks is produced using coelenterazine as the substrate for the luciferin-luciferase reaction, as some luminous bony fishes.

Brain Distribution of Berzosertib: An Ataxia Telangiectasia and Rad3-Related Protein Inhibitor for the Treatment of Glioblastoma.

The effective treatment of brain tumors is a considerable challenge in part because of the presence of the blood-brain barrier (BBB) that limits drug delivery. Glioblastoma multiforme (GBM) is an aggressive and infiltrative primary brain tumor with an extremely poor prognosis after standard-of-care therapy with surgery, radiotherapy (RT), and chemotherapy. DNA damage response (DDR) pathways play a critical role in DNA repair in cancer cells, and inhibition of these pathways can potentially augment RT and chemotherapy tumor cell toxicity. The ataxia telangiectasia and Rad3-related protein (ATR) kinase is a key regulator of the DDR network and is potently and selectively inhibited by the ATR inhibitor berzosertib. Although in vitro studies demonstrate a synergistic effect of berzosertib in combination with temozolomide, in vivo efficacy studies have yet to recapitulate this observation using intracranial tumor models. In the current study, we demonstrate that delivery of berzosertib to the brain is restricted by efflux at the BBB. Berzosertib has a high binding affinity to brain tissue compared with plasma, thereby leading to low free drug concentrations in the brain. Berzosertib distribution is heterogenous within the tumor, wherein concentrations are substantially lower in normal brain and invasive tumor rim (wherein the BBB is intact) when compared with those in the tumor core (wherein the BBB is leaky). These results demonstrate that high tissue binding and limited and heterogenous brain distribution of berzosertib may be important factors that influence the efficacy of berzosertib therapy in GBM. SIGNIFICANCE STATEMENT: This study examined the brain delivery and efficacy of berzosertib in patient-derived xenograft models of glioblastoma multiforme (GBM). Berzosertib is actively effluxed at the blood-brain barrier and is highly bound to brain tissue, leading to low free drug concentrations in the brain. Berzosertib is heterogeneously distributed into different regions of the brain and tumor and, in this study, was not efficacious in vivo when combined with temozolomide. These factors inform the future clinical utility of berzosertib for GBM.

Determination of the Absolute Configuration of Bioactive Indole-Containing Pyrazino[2,1-b]quinazoline-3,6-diones and Study of Their In Vitro Metabolic Profile.

In recent decades, fungi-derived naturally occurring quinazolines have emerged as potential drug candidates. Nevertheless, most studies are conducted for bioactivity assays, and little is known about their absorption, distribution, metabolism, and elimination (ADME) properties. To perform metabolic studies, the synthesis of the naturally occurring quinazolinone, fiscalin B (1), and its chloro derivative, 4-((1H-indol-3-yl)methyl)-8,10-dichloro-1-isobutyl-1,2-dihydro-6H-pyrazino[2,1-b]quinazoline-3,6(4H)-dione (2), disclosed as an antibacterial agent, was performed in a gram scale using a microwave-assisted polycondensation reaction with 22% and 17% yields, respectively. The structure of the non-natural (+)-fiscalin B was established, for the first time, by X-ray crystallography as (1R,4S)-1, and the absolute configuration of the naturally occurring fiscalin B (-)-1 was confirmed by comparison of its calculated and experimental electronic circular dichroism (ECD) spectra as (1S,4R)-1. in vitro metabolic studies were monitored for this class of natural products for the first time by ultra-high-performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS). The metabolic characteristics of 1 and 2 in human liver microsomes indicated hydration and hydroxylation mass changes introduced to the parent drugs.

New Pyrazine Conjugates: Synthesis, Computational Studies, and Antiviral Properties against SARS-CoV-2.

Currently, limited therapeutic options are available for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We have developed a set of pyrazine-based small molecules. A series of pyrazine conjugates was synthesized by microwave-assisted click chemistry and benzotriazole chemistry. All the synthesized conjugates were screened against the SAR-CoV-2 virus and their cytotoxicity was determined. Computational studies were carried out to validate the biological data. Some of the pyrazine-triazole conjugates (5 d-g) and (S)-N-(1-(benzo[d]thiazol-2-yl)-2-phenylethyl)pyrazine-2-carboxamide 12 i show significant potency against SARS-CoV-2 among the synthesized conjugates. The selectivity index (SI) of potent conjugates indicates significant efficacy compared to the reference drug (Favipiravir).

Single Origin Coffee Aroma: From Optimized Flavor Protocols and Coffee Customization to Instrumental Volatile Characterization and Chemometrics.

In this study, the aroma profile of 10 single origin Arabica coffees originating from eight different growing locations, from Central America to Indonesia, was analyzed using Headspace SPME-GC-MS as the analytical method. Their roasting was performed under temperature-time conditions, customized for each sample to reach specific sensory brew characteristics in an attempt to underline the customization of roast profiles and implementation of separate roastings followed by subsequent blending as a means to tailor cup quality. A total of 138 volatile compounds were identified in all coffee samples, mainly furan (~24-41%) and pyrazine (~25-39%) derivatives, many of which are recognized as coffee key odorants, while the main formation mechanism was the Maillard reaction. Volatile compounds' composition data were also chemometrically processed using the HCA Heatmap, PCA and HCA aiming to explore if they meet the expected aroma quality attributes and if they can be an indicator of coffee origin. The desired brew characteristics of the samples were satisfactorily captured from the volatile compounds formed, contributing to the aroma potential of each sample. Furthermore, the volatile compounds presented a strong variation with the applied roasting conditions, meaning lighter roasted samples were efficiently differentiated from darker roasted samples, while roasting degree exceeded the geographical origin of the coffee. The coffee samples were distinguished into two groups, with the first two PCs accounting for 73.66% of the total variation, attributed mainly to the presence of higher quantities of furans and pyrazines, as well as to other chemical classes (e.g., dihydrofuranone and phenol derivatives), while HCA confirmed the above results rendering roasting conditions as the underlying criterion for differentiation.

Functional assessment of the effects of CYP3A4 variants on acalabrutinib metabolism in vitro.

AIM: We aimed (i) to study the effects of genetic polymorphism of cytochrome P450 3A4 (CYP3A4) and drug interactions on acalabrutinib (ACA) metabolism and (ii) to investigate the mechanisms underlying the effects of CYP3A4 variants on the differential kinetic profiles of ACA and ibrutinib. METHOD: Recombinant human CYP3A4 and variants were expressed using a Bac-to-Bac baculovirus expression system. The cell microsome was prepared and subjected to kinetic study. The analyte concentrations were determined by UPLC-MS/MS. A molecular docking assay was employed to investigate the mechanisms leading to differences in kinetic profiles. RESULTS: The kinetic parameters of ACA, catalyzed by CYP3A4 and 28 of its variants, were determined, including Vmax, Km, and Ksi. CYP3A4.6-8, 12, 13, 17, 18, 20, and 30 lost their catalytic function. No significant differences were found for CYP3A4.4, 5, 10, 15, 31, and 34 compared with CYP3A4.1 with respect to intrinsic clearance (Vmax/Km, Clint). However, the Clint values of CYP3A4.9, 14, 16, 19, 23, 24, 28, 32 were obviously decreased, ranging from 0.02 to 0.05 µL/min/pmol. On the contrary, the catalytic activities of CYP3A4.2, 3, 11, 29, and 33 were increased dramatically. The Clint value of CYP3A4.11 was 5.95 times as high as that of CYP3A4.1. Subsequently, CYP3A4.1, 3, 11, 23, and 28 were chosen to study the kinetic changes in combination with ketoconazole. Interestingly, we found the inhibitory potency of ketoconazole varied in different variants. In addition, the kinetic parameters of ibrutinib and ACA were accordingly compared in different CYP3A4 variants. Significant differences in relative clearance were observed among variants, which would probably influence the distance between the redox site and the heme iron atom. CONCLUSION: Genetic polymorphism of CYP3A4 extensively changes its ACA-metabolizing enzymatic activity. In combination with a CYP inhibitor, its inhibitory potency also varied among different variants. Even the same variants exhibited different capabilities catalyzing ACA. Its enzymatic capabilities are probably determined by the distance between the substrate and the heme iron atom, which could be impacted by mutation.

An evolutionary conserved olfactory receptor for foodborne and semiochemical alkylpyrazines.

Molecular recognition is a fundamental principle in biological systems. The olfactory detection of both food and predators via ecological relevant odorant cues are abilities of eminent evolutionary significance for many species. Pyrazines are such volatile cues, some of which act as both human-centered key food odorants (KFOs) and semiochemicals. A pyrazine-selective odorant receptor has been elusive. Here we screened 2,3,5-trimethylpyrazine, a KFO and semiochemical, and 2,5-dihydro-2,4,5-trimethylthiazoline, an innate fear-associated non-KFO, against 616 human odorant receptor variants, in a cell-based luminescence assay. OR5K1 emerged as sole responding receptor. Tested against a comprehensive collection of 178 KFOs, we newly identified 18 pyrazines and (2R/2S)-4-methoxy-2,5-dimethylfuran-3(2H)-one as agonists. Notably, OR5K1 orthologs in mouse and domesticated species displayed a human-like, potency-ranked activation pattern of pyrazines, suggesting a domestication-led co-evolution of OR5K1 and its orthologs. In summary, OR5K1 is a specialized olfactory receptor across mammals for the detection of pyrazine-based key food odors and semiochemicals.