Quarternary structure amplification of protein folding differences observed in ‘native’ platelet factor‐4

FEBS Letters

Barker, Sharon¹  Mayo, Kevin H.¹ 

[1] Department of Biochemistry, Biomedical Engineering Center, University of Minnesota, 420 Delaware Street, S. E., Minneapolis, MN 55455, USA

关键词: Protein folding;    NMR;    Platelet factor 4;    Subunit association;    PF4;    platelet factor 4;    NMR;    nuclear magnetic resonance spectroscopy;    NOE;    nuclear Overhauser effect;    rf;    radio frequency;    FID;    free induction decay;    CD;    circular dichroism;    HPLC;    high performance liquid chromatography;    M;    monomer;    D;    dimer;    T;    tetramer;   

DOI  :  10.1016/0014-5793(94)01384-D

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Platelet factor 4 (PF4), a protein of 70 residues, exists in solution as a distribution of monomer, dimer and tetramer (M-D-T) states in slow exchange on a 600 MHz ¹H-NMR chemical shift time scale. Well-resolved Y60 ring proton resonances in each aggregate state allow derivation of M-D-T populations. Under the same set of solution conditions, M-D-T aggregate state distributions vary from prep to prep or with repeated freeze-drying or raising/lowering the solution pH. These variations are not the result of chemical modifications and reflect differences in the strength of subunit associations and therefore folding. Variations are greatest at pH values at or below the pK_as of carboxylate groups, supporting the idea that electrostatic interactions modulate PF4 subunit interactions. Treating these distributions as true equilibria results in free energy differences of about 0.5 kcal/mol subunit. Quarternary structure amplifies free energy differences among various folded states of monomer PF4.

【 授权许可】

Unknown