Isolation, purification, and characterization of a rat liver mitochondrialprotein disulfide isomerase

The isolation and purification to electrophoretical homogeneity and charact erization of a protein disulfide isomerase from rat liver mitochondria is r eported. The purified enzyme exhibits a single band on sodium dodecylsulfat e-polyacrylamide gel electrophoresis with an apparent molecular weight of a pproximately 54 kDa. Comparatively, the microsomal form shows an apparent m olecular weight of 57 kDa indicating that the two forms are slightly differ ent. The antibody raised against the microsomal isoform does not recognize the mitochondrial enzyme. To characterize the enzyme, different classical m ethodologies utilized for protein disulfide isomerase estimation have been adopted. The isolated enzyme is active with all of them, indicating that it comprises all the features of a typical protein disulfide isomerase. At th e mitochondrial level the enzyme appears mostly localized at the membrane l evel. Its potential involvement in mitochondrial membrane permeability cont rol is also discussed. (C) 2000 Elsevier Science Inc.