STRUCTURE DETERMINATION OF THE N-TERMINAL THIOREDOXIN-LIKE DOMAIN OF PROTEIN DISULFIDE-ISOMERASE USING MULTIDIMENSIONAL HETERONUCLEAR C-13 N-15 NMR-SPECTROSCOPY/

As a first step in dissecting the structure of human protein disulfide isomerase (PDI), the structure of a fragment corresponding to the fir st 120 residues of its sequence has been determined using heteronuclea r multidimensional NMR techniques. As expected from its primary struct ure homology, the fragment has the thioredoxin fold. Similarities and differences in their structures help to explain why thioredoxins are r eductants, whereas PDI is an oxidant of protein thiol groups. The resu lts confirm that PDI has a modular, multidomain structure, which will facilitate its structural and functional characterization.