Protein self-association in solution: the bovine pancreatic trypsin inhibitor decamer.

ABSTRACT: We have used magnetic relaxation dispersion to study bovine pancreatic trypsin inhibitor (BPTI) self-association as a function of pH, salt type and concentration, and temperature. The magnetic relaxation dispersion method sensitively detects stable oligomers without being affected by other interactions. We find that BPTI decamers form cooperatively under a wide range of solution conditions with no sign of dimers or other small oligomers. Decamer formation is opposed by electrostatic repulsion among numerous cationic residues confined within a narrow channel. Accordingly, the decamer population increases with increasing pH, as cationic residues are deprotonated, and with increasing salt concentration. The salt effect cannot be described in terms of Debye screening, but involves the ion-spec

SUBMITTER: Gottschalk M 

PROVIDER: S-EPMC1302976 | biostudies-literature | 2003 Jun

REPOSITORIES: biostudies-literature