Purification and Characterization of the Two Molecular Forms of Membrane Acid Protease from Aspergillus oryzae

Publisher Website
Google Scholar
Abstract
Two forms (M1 and M2) of the membrane-bound acid protease [EC 3.4.23.6] of A. oryzae were purified by extraction with Triton X-100, washing with cold acetone, and repeated gel filtration on Bio-Gel A-15 m in the presence and absence of Triton X-100. The purified membrane enzymes, M1 and M2, moved as a single band in acrylamide gel electrophoresis and had apparent MW of 150,000 and 60,000, respectively, as estimated by sodium dodecyl sulfate/acrylamide gel electrophoresis. These 2 membrane enzymes activated bovine pancreatic trypsinogen and had the same pH optima in the acid pH range. They immunologically cross-reacted with each other and with an extra-cellular acid protease from A. oryzae, and contained carbohydrate, ranging from 52.5-80.5% and comprising 3 hexoses, glucose, galactose and mannose. While these catalytic, chemical and immunological properties are similar to those of the extracellular acid protease from A. oryzae, both membrane enzymes differed in their hydrophobic properties from external enzymes. Thus they are activated by the detergent Triton X-100 and some polar lipids.