TY  - THES
AU  - Avinery, Ram
AU  - Beck-Barkai, Roy
TI  - Forces underlying the conformational selection of myelin basic protein
PB  - Tel-Aviv University
VL  - MS
CY  - Tel-Aviv
M1  - PUBDB-2015-00575
SP  - -
PY  - 2014
N1  - No full text available.
N1  - Tel-Aviv University, Masterarbeit, 2014
AB  - Myelin Basic Protein (MBP) has important biological role in stabilizing and compacting the myelin sheath. Previous evidence suggest that MBP adopts a compact structure when adsorbed to negatively charged membrane and gains flexibility and expands in solution. This inherent flexibility in solution, unlike most proteins, is termed intrinsic disorder. Being highly disordered, MBP adopts a wide variety of conformations simultaneously in solution. Small angle x-ray scattering and analysis using ensemble modelling are used to quantify the conformatioal diversity under varying pH and salt conditions.MBP is a polyampholyte, having both positively and negatively charged monomers with a high excess of positive charge. At pH 7.4 the mean radius of gyration (R_g) of MBP decreases with increasing salts, with a local minimum encountered around 100mM followed by re-swelling and then re-compaction. At pH 10 MBP displays a size minimum near 100mM yet no re-compaction is observed up to 500mM salt concentration. MBP in pH 4 displays R_g trend highly similar to pH 7.4, though always with slightly larger R_g as expected with its increased net charge. Underlying forces are discussed through free energy estimates calculated using polymer physics derivations.MBP’s size minimum at 100mM salt concentration is not entirely consistent with simplistic polyampholyte view, and more likely secondary structure changes are involved. Calculations indicate that salt concentration strongly affects secondary structure selection of MBP by modulating an interplay between electrostatic interaction and polymer chain entropy. The results imply a strategy for designing structural stabilization upon adsorption to a surface.
KW  - Unveröffentlichte Hochschulschrift (GND)
LB  - PUB:(DE-HGF)19
UR  - https://bib-pubdb1.desy.de/record/206042
ER  -