Identifying and characterizing a second structural domain of protein disulfide isomerase

Recent protein engineering studies have confirmed the multidomain nature of protein disulfide isomerase previously suggested on the basis of analysis of its amino acid sequence. The boundaries of three domains, denoted a, a' and b, have been determined, and each domain has been expressed as an indiv idual soluble folded protein. In this report, the boundaries of the final s tructural domain, b', are defined by a combination of restricted proteolysi s and protein engineering approaches to complete our understanding of the d omain organization of PDI. Using these data an optimized polypeptide constr uct has been prepared and characterized with a view to further structural a nd functional studies. (C) 1999 Federation of European Biochemical Societie s.