Heterogeneity of heparin: characterization of one hundred components with different anticoagulant activities by a combination of electrophoretic and affinity chromatography methods

A comparative study of heparin fractions obtained by affinity chromatography, electrofocusing, selective barium precipitation, polyacrylamide and agarose gel electrophoresis is reported. It is concluded that commercial heparin preparations are heterogeneous, containing at least 120 components which differ in molecular weight, in degree of affinity for antithrombin, and in their distribution in monomeric and dimeric forms. High anticoagulant activity for some heparin fractions was obtained by most of the methods used.     

Molecular dynamic simulations of nanomechanic chaperone peptide and effects of in silico His mutations on nanostructured function

The nanoscale peptide YSGVCHTDLHAWHGDWPLPVK exhibits molecular chaperone activity and prevents protein aggregation under chemical and/or thermal stress. Here, His mutations of this peptide and their impact on chaperone activity were evaluated using theoretical techniques. Molecular dynamic (MD) simulations with simulated annealing (SA) of different mutant nanopeptides were employed to determine the contribution of the scaffolding His residues (H45, H49, H52), when mutated to Pro, on chaperone action in vitro. The in silico mutations of His residues to Pro (H45P, H49P, H52P) revealed loss of secondary ordered strand structure. However, a small part of the strand conformation was formed in the middle region of the native chaperone peptide. The His‐to‐Pro mutations resulted in decreased gyration radius (R_g) values and surface accessibility of the mutant peptides under the simulation times. The invariant dihedral angle (ϕ) values and the disrupting effects of the Pro residues indicated the coil conformation of mutant peptides. The failure of the chaperone‐like action in the Pro mutant peptides was consistent with their decreased effective accessible surfaces. The high variation of Φ value for His residues in native chaperone peptide leads to high flexibility, such as a minichaperone acting as a nanomachine at the molecular level. Our findings demonstrate that the peptide strand conformation motif with high flexibility at nanoscale is critical for chaperone activity. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.