Conformational Landscape of N-Glycosylated Peptides Detecting Autoantibodies in Multiple Sclerosis, Revealed by Hamiltonian Replica Exchange

Synthetic N-glycosylated CSF114­(Glc) and related peptides were proved to be able to recognize specific and high-affinity autoantibodies circulating in blood of relapsing-remitting multiple sclerosis (MS) patients and correlating with disease activity. The effect of these peptides has been linked to the β-turn structure around the minimal epitope Asn­(Glc). In this work we performed Hamiltonian replica exchange molecular dynamics simulations on the central heptapeptide fragment of a CSF114­(Glc)-derived peptide in water and in a water/hexafluoroacetone mixture, confirming a significant incidence of β-turn structures in both solvents. The structural similarity of the glycosylated and unglycosylated forms in all environments proves that the conformation of the heptapeptide is only marginally affected by the presence of the sugar. Moreover, the presence of a significant amount of bioactive hairpin-like conformations in the water environment suggests a possible use not only in the diagnosis but also in the treatment of MS

Designed Glucopeptides Mimetics of Myelin Protein Epitopes As Synthetic Probes for the Detection of Autoantibodies, Biomarkers of Multiple Sclerosis

We previously reported that CSF114­(Glc) detects diagnostic autoantibodies in multiple sclerosis sera. We report herein a bioinformatic analysis of myelin proteins and CSF114­(Glc), which led to the identification of five sequences. These glucopeptides were synthesized and tested in enzymatic assays, showing a common minimal epitope. Starting from that, we designed an optimized sequence, SP077, showing a higher homology with both CSF114­(Glc) and the five sequences selected using the bioinformatic approach. SP077 was synthesized and tested on 50 multiple sclerosis patients’ sera, and was able to detect higher antibody titers as compared to CSF114­(Glc). Finally, the conformational properties of SP077 were studied by NMR spectroscopy and structure calculations. Thus, the immunological activity of SP077 in the recognition of specific autoantibodies in multiple sclerosis patients’ sera may be ascribed to both the optimized design of its epitopic region and the superior surface interacting properties of its C-terminal region

Conformational Analysis of Gly–Ala–NHMe in D₂O and DMSO Solutions: A Two-Dimensional Infrared Spectroscopy Study

A relevant number of experiments on short peptides has been performed in recent years. One of the major problems rises from the simultaneous presence of slightly different conformers at equilibrium in solution. In the present paper, the conformational characteristics of the Gly–l-Ala–Methyl amide dipeptide in D₂O and DMSO solutions are investigated by nonlinear IR spectroscopy. The pump–probe scheme with ultrashort mid-infrared pulses, in the Amide I region, is used to determine the mutual orientation of the two CO bonds and the dynamics due to solute–solvent interactions. The coupling between Amide I modes is evaluated from both linear and 2D spectra. The interconversion between the different conformations occurs on time scales longer than the vibrational lifetime, and the spectral diffusion observed in 2D spectra is attributed to the solvent dynamics. Quantum mechanical calculations and molecular dynamics simulations are performed to identify the most stable geometries. By comparing the experimental and the theoretical data, we establish the prevalence of β-like polar conformers in both water and DMSO solvents

Relationships among DEHP metabolites concentrations in urine normalized by creatinine (expressed as μg/g) in obese children.

<p>C.A.: chronological age; HtSDS: height expressed as standard deviation score. BMISDS: Body mass index expressed as standard deviation score.</p><p>FGIR: Fasting glucose to insulin ratio; WBISI: Whole Body Insulin Sensitivity Index; AUCI: Area under the curve for insulin calculated from the from the Oral Glucose Tolerance Test (OGTT).</p><p>Relationships among DEHP metabolites concentrations in urine normalized by creatinine (expressed as μg/g) in obese children.</p

Geographical distribution of the obese and normal-weight subjects.

<p>The children came from a small area within the Emilia-Romagna region in Italy, mainly between the provinces of Parma and Reggio-Emilia.</p

Concentration of DEHP metabolites in urine normalized by creatinine (espressed as μg/g).

<p>Reported results are from Kruskall-Wallis ANOVA.</p><p>Data are median (25^th-75^th percentile);</p><p>vs: versus.</p><p>Concentration of DEHP metabolites in urine normalized by creatinine (espressed as μg/g).</p

Metabolism of DEHP.

<p>(A) Hydrolytic/oxidative pathway leading to MEHP and secondary metabolite formation. (B) Formation of glucuronic conjugates of DEHP metabolites.</p

Relationships among DEHP metabolites concentration in urine normalized by creatinine (espressed as μg/g) in normal-weight children.

<p>5-oxo-MEHP correlated positively with both HtSDS (rho:0.579; p<0.002) and BMISDS (rho:0.441; p<0.015; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0117831#pone.0117831.t005" target="_blank">Table 5</a>).</p><p>Relationships among DEHP metabolites concentration in urine normalized by creatinine (espressed as μg/g) in normal-weight children.</p

Concentration and distribution of single DEHP metabolites in urine.

<p>(A) control subject and (B) obese children and adolescents.</p

Semantic Connectivity Map linking DEHP metabolites.

<p>Analysis with auxological parameters and measurements of insulin sensitivity in normal-weight and obese children and adolescents. Values ranging from 0 (no association) to 1 (the strongest association) express the strength of association.</p