A statistical approach to the calculation of conformation of proteins. 2. The reoxidation of reduced trypsin inhibitor.

A statistical method for the calculation of conformation is applied to the small protein, basic pancreatic trypsin inhibitor. The polypeptide geometry, energies, rotational isomers, and technique of conformation generation are discussed in detail. The calculations indicate that (i) under denaturing conditions, reduced trypsin inhibitor when oxidized should form initially 14 of the 15 possible single disulfide bridge intermediates in roughly equal proportions, and (ii) under renaturing conditions (pH 8.7, room temperature, aqueous solution) the single disulfide bridge intermediate with cys 30 and cys 51 connected is present in higher concentration than that with cys 30 and cys 55 linked. The two calculations are in agreement with experiment.