Nonspecific hydrophobic interactions stabilize an equilibrium intermediate of apomyoglobin at a key position within the AGH region.

ABSTRACT: Acid-induced unfolding of apomyoglobin (apoMb) proceeds in a multistate process involving at least one equilibrium intermediate (I) at pH 4.2. The structure of the I form has been investigated thoroughly, with significant effort devoted to identifying potentially stabilizing native contacts. Here, we test whether rigid side-chain packing interactions like those in holomyoglobin persist at a buried position, Met-131, within the low-pH apoMb intermediate. We have measured the urea-induced unfolding transitions of overpacking, underpacking, and polar substitutions of Met-131 to determine the effect on the stability of the native and intermediate states of apoMb. Whereas underpacking substitutions should destabilize the I form irrespective of the degree of native side-chain-packing interaction

SUBMITTER: Bertagna AM 

PROVIDER: S-EPMC515089 | biostudies-literature | 2004 Aug

REPOSITORIES: biostudies-literature