Unveiling the Oxazolidine Character of Pseudoproline Derivatives by Automated Flow Peptide Chemistry.

Pseudoproline derivatives such as Thr(ΨPro)-OH are commonly used in peptide synthesis to reduce the likelihood of peptide aggregation and to prevent aspartimide (Asi) formation during the synthesis process. In this study, we investigate notable by-products such as aspartimide formation and an imine derivative of the Thr(ΨPro) moiety observed in flow peptide chemistry synthesis. To gain insight into the formation of these unexpected by-products, we design a series of experiments. Furthermore, we demonstrate the oxazolidine character of the pseudoproline moiety and provide plausible mechanisms for the two-way ring opening of oxazolidine leading to these by-products. In addition, we present evidence that Asi formation appears to be catalyzed by the presence of the pseudoproline moiety. These observed side reactions are attributed to elevated temperature and pressure; therefore, caution is advised when using ΨPro derivatives under such harsh conditions. In addition, we propose a solution whereby thermodynamically controlled Asi formation can be kinetically prevented.

Compactness of Protein Folds Alters Disulfide-Bond Reducibility by Three Orders of Magnitude: A Comprehensive Kinetic Case Study on the Reduction of Differently Sized Tryptophan Cage Model Proteins.

A new approach to monitor disulfide-bond reduction in the vicinity of aromatic cluster(s) has been derived by using the near-UV range (λ=266-293 nm) of electronic circular dichroism (ECD) spectra. By combining the results from NMR and ECD spectroscopy, the 3D fold characteristics and associated reduction rate constants (k) of E19_SS, which is a highly thermostable, disulfide-bond reinforced 39-amino acid long exenatide mimetic, and its N-terminally truncated derivatives have been determined under different experimental conditions. Single disulfide bond reduction of the E19_SS model (with an 18-fold excess of tris(2-carboxyethyl)phosphine, pH 7, 37 °C) takes hours, which is 20-30 times longer than that expected, and thus, would not reach completion by applying commonly used reduction protocols. It is found that structural, steric, and electrostatic factors influence the reduction rate, resulting in orders of magnitude differences in reduction half-lives (900>t1/2 >1 min) even for structurally similar, well-folded derivatives of a small model protein.

Pregabalin adjunctive therapy for focal onset seizures in children 1 month to <4 years of age: A double-blind, placebo-controlled, video-electroencephalographic trial.

OBJECTIVE: To evaluate the efficacy and safety of pregabalin as adjunctive treatment for children (aged 1 month-<4 years) with focal onset seizures (FOS) using video-electroencephalography (V-EEG). METHODS: This randomized, placebo-controlled, international study included V-EEG seizure monitoring (48-72 hours) at baseline and over the last 3 days of 14-day (5-day dose escalation; 9-day fixed dose) double-blind pregabalin treatment (7 or 14 mg/kg/d in three divided doses). This was followed by a double-blind 1-week taper. The primary efficacy endpoint was log-transformed seizure rate (loge [24-hour seizure rate + 1]) for all FOS recorded during the double-blind V-EEG monitoring, evaluated in subjects who took ≥1 dose of study medication, experienced ≥1 baseline seizure(s), and had a treatment phase V-EEG. Safety and tolerability were assessed by adverse events (AEs), clinical laboratory data, physical/neurological examinations, vital signs, and electrocardiograms. RESULTS: Overall, 175 patients were randomized (mean age = 28.2 months; 59% male, 69% white, 30% Asian) in a 2:1:2 ratio to pregabalin 7 or 14 mg/kg/d (n = 71 or n = 34, respectively), or placebo (n = 70). Pregabalin 14 mg/kg/d (n = 28) resulted in a statistically significant 35% reduction of loge (24-hour seizure rate + 1) versus placebo (n = 53; P = .022), an effect that was not observed with pregabalin 7 mg/kg/d (n = 59; P = .461). The most frequently reported treatment-emergent AEs for pregabalin 7 mg/kg/d, 14 mg/kg/d, and placebo, respectively, were somnolence (11.3%, 17.6%, and 5.7%) and upper respiratory tract infection (7.0%, 11.8%, and 11.4%). All AEs were mild to moderate in severity. SIGNIFICANCE: Pregabalin 14 mg/kg/d (but not 7 mg/kg/d) significantly reduced seizure rate in children with FOS, when assessed using V-EEG, compared with placebo. Both pregabalin dosages were generally safe and well tolerated in children 1 month to <4 years of age with FOS. Safety and tolerability were consistent with the known profile of pregabalin in older children with epilepsy.

Assignment of Vibrational Circular Dichroism Cross-Referenced Electronic Circular Dichroism Spectra of Flexible Foldamer Building Blocks: Towards Assigning Pure Chiroptical Properties of Foldamers.

Assignment of the most established electronic circular dichroism (ECD) spectra of polypeptides and foldamers is either "evidence based" or relies on the 3D structures of longer oligomers of limited internal dynamics, which are derived from NMR spectroscopy (or X-ray) data. Critics warn that the use of NMR spectroscopy and ECD side by side has severe limitations for flexible molecules because explicit knowledge of conformational ensembles is a challenge. Herein, an old-new method of comparing ab initio computed and measured vibrational circular dichroism (VCD) data is presented to validate both the structures (conf(i)) and their relative weights (c(i)) that make up the conformational ensemble. Based on the array of {conf(i), c(i)}, the pure ECD spectra, g(i)conf(i) , can be ab initio calculated. The reconstructed spectrum Σc(i)g(i)conf(i) can thus help to assign any experimental ECD counterparts. Herein, such a protocol is successfully applied to flexible foldamer building blocks of sugar ß-amino acid diamides. The epimeric pair of the model system was selected because these molecules were conformationally tunable by simple chemical modification, and thus, the robustness of the current approach could be probed. The initial hydrogen bond (NH⋅⋅⋅O) eliminated by N-methylation reorients the amide plain, which influences the chiroptical properties of the foldamer building block; this structural change is successfully monitored by changes to the VCD and ECD transitions, which are now assigned to pure conformers. The current method seems to be general and effective without requiring extensive CPU and spectroscopic resources.

α/ß-Chimera peptide synthesis with cyclic ß-sugar amino acids: the efficient coupling protocol.

The synthesis of α/ß-chimeras comprises peptide bond formation from α- to ß-, from ß- to ß-, and from ß- to α-amino acid residues. The fine-tuned solid phase synthesis of -GXXG- chimera peptides containing the simplest achiral α-amino acid glycine and two cyclic SAAs of different ring size [X denoting cyclic ß-Sugar Amino Acids (ß-SAA)] is reported, variants containing Fmoc-RibAFU(ip)-OH a furanoid-, and Fmoc-GlcAPU(Me)-OH a pyranoid-type structural "Lego-element". Systematic search for the best coupling strategy with both H-ß-SAA-OHs is described, including the comparison of the different coupling reagents and conditions. Selecting the optimal reagent (from commonly used PyBOP, HATU and HOBt) was assisted by time-resolved 1H-NMR: formation and stability of the Fmoc protected active esters were compared. We found that PyBOP is the best choice for successfully coupling both H-ß-SAA-OH prototypes. The present comparative results open a reasonable route for building efficiently various -ß-SAA- containing homo- and heterooligomers.

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin-GnRH-III conjugates developed for targeted drug delivery.

Gonadotropin releasing hormone-III (GnRH-III), a native isoform of the human GnRH isolated from sea lamprey, specifically binds to GnRH receptors on cancer cells enabling its application as targeting moieties for anticancer drugs. Recently, we reported on the identification of a novel daunorubicin-GnRH-III conjugate (GnRH-III-[4Lys(Bu), 8Lys(Dau=Aoa)] with efficient in vitro and in vivo antitumor activity. To get a deeper insight into the mechanism of action of our lead compound, the cellular uptake was followed by confocal laser scanning microscopy. Hereby, the drug daunorubicin could be visualized in different subcellular compartments by following the localization of the drug in a time-dependent manner. Colocalization studies were carried out to prove the presence of the drug in lysosomes (early stage) and on its site of action (nuclei after 10 min). Additional flow cytometry studies demonstrated that the cellular uptake of the bioconjugate was inhibited in the presence of the competitive ligand triptorelin indicating a receptor-mediated pathway. For comparative purpose, six novel daunorubicin-GnRH-III bioconjugates have been synthesized and biochemically characterized in which 6Asp was replaced by D-Asp, D-Glu and D-Trp. In addition to the analysis of the in vitro cytostatic effect and cellular uptake, receptor binding studies with 125I-triptorelin as radiotracer and degradation of the GnRH-III conjugates in the presence of rat liver lysosomal homogenate have been performed. All derivatives showed high binding affinities to GnRH receptors and displayed in vitro cytostatic effects on HT-29 and MCF-7 cancer cells with IC50 values in a low micromolar range. Moreover, we found that the release of the active drug metabolite and the cellular uptake of the bioconjugates were strongly affected by the amino acid exchange which in turn had an impact on the antitumor activity of the bioconjugates.

C-3 epimers of sugar amino acids as foldameric building blocks: improved synthesis, useful derivatives, coupling strategies.

To obtain key sugar derivatives for making homooligomeric foldamers or α/ß-chimera peptides, economic and multigram scale synthetic methods were to be developed. Though described in the literature, the cost-effective making of both 3-amino-3-deoxy-ribofuranuronic acid (H-t X-OH) and its C-3 epimeric stereoisomer, the 3-amino-3-deoxy-xylofuranuronic acid (H-c X-OH) from D-glucose is described here. The present synthetic route elaborated is (1) appropriate for large-scale synthesis; (2) reagent costs reduced (e.g. by a factor of 400); (3) yields optimized are ~80% or higher for all six consecutive steps concluding -t X- or -c X- and (4) reaction times shortened. Thus, a new synthetic route step-by-step optimized for yield, cost, time and purification is given both for D-xylo and D-ribo-amino-furanuronic acids using sustainable chemistry (e.g. less chromatography with organic solvents; using continuous-flow reactor). Our study encompasses necessary building blocks (e.g. -X-OMe, -X-OiPr, -X-NHMe, Fmoc-X-OH) and key coupling reactions making -Aaa-t X-Aaa- or -Aaa-t X-t X-Aaa- type "inserts". Completed for both stereoisomers of X, including the newly synthesized Fmoc-c X-OH, producing longer oligomers for drug design and discovery is more of a reality than a wish.

Aromatic Cluster Sensor of Protein Folding: Near-UV Electronic Circular Dichroism Bands Assigned to Fold Compactness.

Both far- and near-UV electronic circular dichroism (ECD) spectra have bands sensitive to thermal unfolding of Trp and Tyr residues containing proteins. Beside spectral changes at 222 nm reporting secondary structural variations (far-UV range), Lb bands (near-UV range) are applicable as 3D-fold sensors of protein's core structure. In this study we show that both Lb (Tyr) and Lb (Trp) ECD bands could be used as sensors of fold compactness. ECD is a relative method and thus requires NMR referencing and cross-validation, also provided here. The ensemble of 204 ECD spectra of Trp-cage miniproteins is analysed as a training set for "calibrating" Trp↔Tyr folded systems of known NMR structure. While in the far-UV ECD spectra changes are linear as a function of the temperature, near-UV ECD data indicate a non-linear and thus, cooperative unfolding mechanism of these proteins. Ensemble of ECD spectra deconvoluted gives both conformational weights and insight to a protein folding↔unfolding mechanism. We found that the Lb293 band is reporting on the 3D-structure compactness. In addition, the pure near-UV ECD spectrum of the unfolded state is described here for the first time. Thus, ECD folding information now validated can be applied with confidence in a large thermal window (5≤T≤85 °C) compared to NMR for studying the unfolding of Trp↔Tyr residue pairs. In conclusion, folding propensities of important proteins (RNA polymerase II, ubiquitin protein ligase, tryptase-inhibitor etc.) can now be analysed with higher confidence.

Origin of problems related to Staudinger reduction in carbopeptoid syntheses.

We report the solid phase synthesis of -GG-X-GG- type α/ß-carbopeptoids incorporating RibAFU(ip) (1a, tX) or XylAFU(ip) (2a, cX) sugar amino acids. Though coupling efficacy is moderate, both the lengthier synthetic route using Fmoc derivative (e.g., Fmoc-RibAFU(ip)-OH) and the azido derivative (e.g., N3-RibAFU(ip)-OH) via Staudinger reaction with nBu3P can be successfully applied. Both X-ray diffraction, 1H- and 31P-NMR, and theoretical (QM) data support and explain why the application of Ph3P as Staudinger reagent is "ineffective" in the case of a cis stereoisomer, if cX is attached to the preceding residue with a peptide (-CONH-) bond. The failure of the polypeptide chain elongation with N3-cX originates from the "coincidence" of a steric crowdedness and an electronic effect disabling the mandatory nucleophilic attack during the hydrolysis of a quasi penta-coordinated triphenylphosphinimine. Nevertheless, the synthesis of the above α/ß-chimera peptides as completed now by a new pathway via 1,2-O-isopropylidene-3-azido-3-deoxy-ribo- and -xylo-furanuronic acid (H-RibAFU(ip)-OH 1a and H-XylAFU(ip)-OH 2a) coupled with N-protected α-amino acids on solid phase could serve as useful examples and starting points of further synthetic efforts.

Efficacy and tolerability of zolmitriptan nasal spray for the treatment of acute migraine in adolescents: Results of a randomized, double-blind, multi-center, parallel-group study (TEENZ).

OBJECTIVE: The primary objective of the TEENZ Study (NCT01211145) was to assess the efficacy of zolmitriptan nasal spray in the acute treatment of adolescent migraine patients (ages 12 to 17 years), as measured by the primary outcome variable of pain-free status at 2 hours post-treatment. METHODS: This randomized, double-blind, placebo-controlled, four-arm parallel group study compared zolmitriptan nasal spray with placebo in the treatment of a single episode of adolescent migraine. Patients completed a 30-day run-in period to treat a single migraine attack with single-blind placebo nasal spray. Eligible patients, who had not responded to placebo, were randomized to one of three zolmitriptan nasal spray doses (5, 2.5, or 0.5 mg) or placebo in a ratio of 5:3:3:5 according to a computer-generated randomization scheme. Patients completed diaries for 24 hours after treatment, recording headache pain scores, adverse events (AEs), and medications taken. RESULTS: In an interim futility analysis, zolmitriptan nasal spray doses of 0.5 and 2.5 mg were declared futile relative to placebo and further randomization to these treatment arms was discontinued. Of 1653 patients enrolled into the study, 855 patients failed to meet study eligibility criteria and were considered screen failures. The most common reason for screen failure was response to placebo challenge (325 patients [38.0%]). Of the 798 patients who were randomized to treatment, 721 (90.4%) completed the study period. Of these, 657 (82.3%) treated a migraine within the study period and contributed data for analysis. Zolmitriptan nasal spray 5 mg was significantly more effective than placebo in achieving pain-free status at 2 hours after treatment (P < .001), with 30% of patients achieving pain-free status at 2 hours vs 17% of placebo-treated patients (OR 2.18; 95% CI 1.40, 3.39). Zolmitriptan nasal spray 5 mg was also more effective than placebo in achieving pain-free status at 3 and 4 hours post-treatment (45 vs 24%, and 56 vs 39%; both P < .001). Zolmitriptan nasal spray 5 mg was also more effective than placebo in achieving headache response at 2, 3, and 4 hours after treatment (51 vs 39%, 61 vs 48%, and 69 vs 57%, respectively; all P ≤ .011). Zolmitriptan nasal spray was well-tolerated at all doses. Dysgeusia was the most frequently reported AE, with greater frequencies reported in active treatment groups versus placebo. No serious AEs or AEs leading to discontinuation were reported. Most AEs were mild or moderate in severity, and consistent with the known profile of zolmitriptan in adult and adolescent populations. CONCLUSION: Zolmitriptan nasal spray was well-tolerated in the acute treatment of adolescent (ages 12 to 17 years) migraine. Zolmitriptan 5 mg nasal spray demonstrated superior efficacy compared with placebo for the primary efficacy endpoint of pain-free status 2 hours after treatment and the efficacy of the 5 mg dose was supported by the majority of secondary efficacy endpoints.

Chiral Recognition Studies of α-(Nonafluoro-tert-butoxy)carboxylic Acids by NMR Spectroscopy.

Three chiral α-(nonafluoro-tert-butoxy)carboxylic acids (R)-1, (RS)-2, (R)-3 were synthesized to examine their application as chiral solvating agents with amines. As a model compound, first (S)- and/or (RS)-α-phenylethylamine was used, and their diastereomeric salts were investigated by (1)H and (19)F NMR and ECD spectroscopy. The NMR spectroscopic studies were carried out at room temperature using the slightly polar CDCl3 and apolar C6D6 as solvents in 5 mM and 54 mM concentrations. The difference of the chemical shifts (Δδ) in the diastereomeric complexes is comparable with other, well-known chiral derivatizing and solvating agents (e.g., Mosher's acid, Pirkle's alcohol). Diastereomeric salts of racemic acids (RS)-1 and (RS)-2 with biologically active amines (1R,2S)-ephedrine and (S)-dapoxetine were also investigated by (19)F NMR spectroscopy.

Rational design of α-helix-stabilized exendin-4 analogues.

Exendin-4 (Ex4) is a potent glucagon-like peptide-1 receptor agonist, a drug regulating the plasma glucose level of patients suffering from type 2 diabetes. The molecule's poor solubility and its readiness to form aggregates increase the likelihood of unwanted side effects. Therefore, we designed Ex4 analogues with improved structural characteristics and better water solubility. Rational design was started from the parent 20-amino acid, well-folded Trp cage (TC) miniprotein and involved the step-by-step N-terminal elongation of the TC head, resulting in the 39-amino acid Ex4 analogue, E19. Helical propensity coupled to tertiary structure compactness was monitored and quantitatively analyzed by electronic circular dichroism and nuclear magnetic resonance (NMR) spectroscopy for the 14 peptides of different lengths. Both (15)N relaxation- and diffusion-ordered NMR measurements were established to investigate the inherent mobility and self-association propensity of Ex4 and E19. Our designed E19 molecule has the same tertiary structure as Ex4 but is more helical than Ex4 under all studied conditions; it is less prone to oligomerization and has preserved biological activity. These conditions make E19 a perfect lead compound for further drug discovery. We believe that this structural study improves our understanding of the relationship between local molecular features and global physicochemical properties such as water solubility and could help in the development of more potent Ex4 analogues with improved pharmacokinetic properties.

On the mechanism of bifunctional squaramide-catalyzed organocatalytic Michael addition: a protonated catalyst as an oxyanion hole.

A joint experimental-theoretical study of a bifunctional squaramide-amine-catalyzed Michael addition reaction between 1,3-dioxo nucleophiles and nitrostyrene has been undertaken to gain insight into the nature of bifunctional organocatalytic activation. For this highly stereoselective reaction, three previously proposed mechanistic scenarios for the critical CC bond-formation step were examined. Accordingly, the formation of the major stereoisomeric products is most plausible by one of the bifunctional pathways that involve electrophile activation by the protonated amine group of the catalyst. However, some of the minor product isomers are also accessible through alternative reaction routes. Structural analysis of transition states points to the structural invariance of certain fragments of the transition state, such as the protonated catalyst and the anionic fragment of approaching reactants. Our topological analysis provides deeper insight and a more general understanding of bifunctional noncovalent organocatalysis.

[Organization of the National Neurofibromatosis Register and areas of application]. / A Nemzeti Neurofibromatózis Regiszter létrehozása és felhasználási területei.

BACKGROUND AND PURPOSE: The neurofibromatosis is a rare genetic disease with increased tumor growing ability and different special symptoms (Riccardi-criteria). The National NF Register has been organized by NF Hungary in 2011. The idea was initiated by hungarian neurofibromatosis experts. METHODS: The register contains data about the primary care physician, the hospital and the patient. The data are recorded by retrospective method and followed in time, so the register can track progress. Furthermore, the register has valid nutrition, physical activity and psychological data, so the users are able to make comparisons with the clinical information. RESULTS: 225 persons are registerd in the system on NF Hungary and 37 patients belong to the NF National Register. The number of patients, who are members of the registry, is always increasing. From the 37 persons 22 are females (60%) and 15 males (40%), 18 adults (48%) and 19 minors (52%). CONCLUSION: NF Register is a very useful system to do research and to draw public health and popolazione conclusions. The register enhances the morbidity details (time of manifestation, progression, prognostic factors, prognosis), thereby could improve the cooperation and the coverage of the patients. The system is open to the patients as well, so it can give them information about new scientific results, new medical treatments and currently availavable medications.

Opening Amyloid-Windows to the secondary structure of proteins: The amyloidogenecity increases tenfold inside beta-sheets.

Methods from artificial intelligence (AI), in general, and machine learning, in particular, have kept conquering new territories in numerous areas of science. Most of the applications of these techniques are restricted to the classification of large data sets, but new scientific knowledge can seldom be inferred from these tools. Here we show that an AI-based amyloidogenecity predictor can strongly differentiate the border- and the internal hexamers of ß-pleated sheets when screening all the Protein Data Bank-deposited homology-filtered protein structures. Our main result shows that more than 30% of internal hexamers of ß sheets are predicted to be amyloidogenic, while just outside the border regions, only 3% are predicted as such. This result may elucidate a general protection mechanism of proteins against turning into amyloids: if the borders of ß-sheets were amyloidogenic, then the whole ß sheet could turn more easily into an insoluble amyloid-structure, characterized by periodically repeated parallel ß-sheets. We also present that no analogous phenomenon exists on the borders of α-helices or randomly chosen subsequences of the studied protein structures.

Influence of Aza-Glycine Substitution on the Internalization of Penetratin.

The cell-penetrating peptide (CPP) penetratin has gained much attention over many years due to its potential role as a transporter for a broad range of cargo into cells. The modification of penetratin has been extensively investigated too. Aza-peptides are peptide analogs in which one or more of the amino residues are replaced by a semicarbazide. This substitution results in conformational restrictions and modifications in hydrogen bonding properties, which affect the structure and may lead to enhanced activity and selectivity of the modified peptide. In this work, the Trp residues of penetratin were substituted by aza-glycine or glycine residues to examine the effect of these modifications on the cellular uptake and the internalization mechanism. The substitution of Trp48 or Trp48,56 dramatically reduced the internalization, showing the importance of Trp48 in cellular uptake. Interestingly, while aza-glycine in the position of Trp56 increased the cellular uptake, Gly reduced it. The two Trp-modified derivatives showed altered internalization pathways, too. Based on our knowledge, this is the first study about the effect of aza-amino acid substitution on the cell entry of CPPs. Our results suggest that aza-amino acid insertion is a useful modification to change the internalization of a CPP.

Neighbor effect on conformational spaces of alanine residue in azapeptides.

The conformational properties of Alanine (Ala) residue have been investigated to understand protein folding and develop force fields. In this work, we examined the neighbor effect on the conformational spaces of Ala residue using model azapeptides, Ac-Ala-azaGly-NHMe (3, AaG), and Ac-azaGly-Ala-NHMe (4, aGA1). Ramachandran energy maps were generated by scanning (φ, ψ) dihedral angles of the Ala residues in models with the fixed dihedral angles (φ = ±90°, ψ = ±0° or ±180°) of azaGly residue using LCgau-BOP and LCgau-BOP + LRD functionals in the gas and water phases. The integral-equation-formalism polarizable continuum model (IEF-PCM) and a solvation model density (SMD) were employed to mimic the solvation effect. The most favorable conformation of Ala residue in azapeptide models is found as the polyproline II (ßP), inverse γ-turn (γ'), ß-sheet (ßS), right-handed helix (αR), or left-handed helix (αL) depending on the conformation of neighbor azaGly residue in isolated form. Solvation methods exhibit that the Ala residue favors the ßP, δR, and αR conformations regardless of its position in azapeptides 3 and 4 in water. Azapeptide 5, Ac-azaGly-Ala-NH2 (aGA2), was synthesized to evaluate the theoretical results. The X-ray structure showed that azaGly residue adopts the polyproline II (ßP) and Ala residue adopts the right-handed helical (αR) structure in aGA2. The conformational preferences of aGA2 and the dimer structure of aGA2 based on the X-ray structure were examined to assess the performance of DFT functionals. In addition, the local minima of azapeptide 6, Ac-Phe-azaGly-NH2 (FaG), were compared with the previous experimental results. SMD/LCgau-BOP + LRD methods agreed well with the reported experimental results. The results suggest the importance of weak dispersion interactions, neighbor effect, and solvent influence in the conformational preferences of Ala residue in model azapeptides.

Lymphocyte subsets in pediatric migraine.

Aseptic inflammation due to activated immune cells has been implicated in the pathomechanism of migraine. We measured the prevalence of regulatory T cells (Tregs), along with that of CD4(+)/CD8(+) lymphocytes and their Th1/Th2 commitment in pediatric migraine. Children and adolescents suffering from migraine without aura, migraine with aura and hemiplegic migraine ictally (n = 53, 27, and 20, respectively), also interictally (n = 33) were recruited and compared to 24 healthy children. Our results indicated comparable prevalence of Tregs, CD4(+) and Th1/Th2 committed cells. CD8(+) prevalence was lower, and CD4(+)/CD8(+) ratio was higher in ictal phase irrespective of the subtype of migraine. No association between CD8(+) prevalence and gender, body weight, disease onset and attack duration in migraine subtypes was found. CD8(+) prevalence was normal in patients in interictal phase. These results suggest the absence of major systemic alteration of adaptive immunity in children and adolescents suffering from migraine; however, a transient decrease of CD8(+) prevalence during the ictal phase was detected irrespective of the subtype of migraine.

Succinct Amyloid and Nonamyloid Patterns in Hexapeptides.

Hexapeptides are widely applied as a model system for studying the amyloid-forming properties of polypeptides, including proteins. Recently, large experimental databases have become publicly available with amyloidogenic labels. Using these data sets for training and testing purposes, one may build artificial intelligence (AI)-based classifiers for predicting the amyloid state of peptides. In our previous work (Biomolecules 2021, 11, 500), we described the Support Vector Machine (SVM)-based Budapest Amyloid Predictor (https://pitgroup.org/bap). Here, we apply the Budapest Amyloid Predictor for discovering numerous amyloidogenic and nonamyloidogenic hexapeptide patterns with accuracy between 80% and 84%, as surprising and succinct novel rules for further understanding the amyloid state of peptides. For example, we have shown that for any independently mutated residue (position marked by "x"), the patterns CxFLWx, FxFLFx, or xxIVIV are predicted to be amyloidogenic, while those of PxDxxx, xxKxEx, and xxPQxx are nonamyloidogenic. We note that each amyloidogenic pattern with two x's (e.g.,CxFLWx) describes succinctly 202 = 400 hexapeptides, while the nonamyloidogenic patterns comprising four point mutations (e.g.,PxDxxx) give 204 = 160 000 hexapeptides in total. We also examine the restricted substitutions for positions "x" from subclasses of proteinogenic amino acid residues; for example, if "x" is substituted with hydrophobic amino acids, then there exist patterns containing three x's, like MxVVxx, predicted to be amyloidogenic. If we can choose for the x positions any hydrophobic amino acids, except the "structure breaker" proline, then we get amyloid patterns with five x positions, for example, xxxFxx, each corresponding to 32 768 hexapeptides. To our knowledge, no similar applications of artificial intelligence tools or succinct amyloid patterns were described before the present work.

Cooperativity network of Trp-cage miniproteins: probing salt-bridges.

Trp-cage miniprotein was used to investigate the role of a salt-bridge (Asp(9) -Arg(16) ) in protein formation, by mutating residues at both sides, we mapped its contribution to overall stability and its role in folding mechanism. We found that both of the above side-chains are also part of a dense interaction network composed of electrostatic, H-bonding, hydrophobic, etc. components. To elucidate the fold stabilizing effects, we compared and contrasted electronic circular dichroism and NMR data of miniproteins equipped with a salt-bridge with those of the salt-bridge deleted mutants. Data were acquired both in neutral and in acidic aqueous solutions to decipher the pH dependency of both fully and partially charged partners. Our results indicate that the folding of Trp-cage miniproteins is more complex than a simple two-state process as we detected an intermediate state that differs significantly from the native fold. The intermediate formation is related to the salt-bridge stabilization; in the miniprotein variants equipped with salt-bridge the population of the intermediate state at acidic pH is significantly higher than it is for the salt-bridge deleted mutants. In this molecular framework Arg(16) stabilizes more than Asp(9) does, because of its higher degree of 3D-fold cooperation. In conclusion, the Xxx(9) leftright arrow Xxx(16) salt-bridge is not an isolated entity of this fold; rather it is an integrated part of a complex interaction network.