Hydrogen?Deuterium Exchange in the Genetic Variants A, B and C of Bovine ß-Lactoglobulin

Abstract

The hydrogen-deuterium exchange in the p-Iactoglobulin genetic variants A, Band C was studied by using an infrared spectrophotometric technique. Between pD 3· 1 and 7· 6 the exchange behaviour of all three proteins was identical, within the limits of experimental accuracy. Conformation transitions that result in changes in specific optical rotation between pH 4 and 6 for each of the proteins could not be detected by means of the hydrogen exchange measurements, suggesting that this particular conformation change is either very small in terms of the numbers of peptide groups involved, or is limited to rapidly exchanging surface groups. In the pD range studied the exchange of all three proteins was consistent with the EX2 mechanism.