The relation of the rotatory dispersion behaviour of human serum albumin to its configuration

Abstract

Optical rotatory dispersion has been used as a means of studying structural changes in human serum albumin under various environmental conditions. The spectropolari-meter is described and a summary of the theoretical basis for the interpretations included. The effects of protein concentration, ionic strength, pH, urea and 2-chloroethanol are described. Albumin is unaffected by pH in the range 4-9 but outside this range configurational changes occur. Urea is shown to decrease the [alpha]-helix content and 2-chloroethanol to increase it. Conditions causing irreversible denaturation are discussed and the introduction of intermolecular hydrogen bonding into the albumin structure is suggested. The albumin molecule is thought of as a single folded polypeptide chain with some 50% of right-handed [alpha]-helix. It appears fairly stable and changes are reversible unless the conditions are sufficiently drastic to cause .S.S. exchange.