Structural aspects of the Mucor bacilliformis proteinase, a new member of the aspartyl-proteinase family.

Bovine chymosin is considered the best milk-clotting enzyme for cheese manufacture; however, the thermophilic Mucor pusillus proteinase is also used nowadays. We herein report structural aspects of the aspartyl proteinase from the local mesophilic Mucor bacilliformis strain. Sequence data indicate a high similarity degree to those of other family members.

Purification and characterization of an acid proteinase from mesophilic Mucor sp. solid-state cultures.

The fourth-day extract of a solid-state culture of the mesophilic Mucor sp. (M-105) strain showed a high milk-clotting activity and a clotting/proteolytic activity ratio similar to that of commercial preparations from microbial origin used in cheese manufacture. After ultrafiltration of the crude extract, the milk-clotting proteinase was purified in two steps: ion-exchange followed by size-exclusion chromatography.

Inhibition of erythrocyte aminolevulinate dehydratase by a 56.2-kD peptide from uremic plasma.

Among the abnormalities in erythrocyte porphyrin metabolism already described in patients with chronic renal failure on hemodialysis, a decrease in blood aminolevulinate dehydratase activity has been reported, suggesting the presence in uremic plasma of an inhibitor of the enzyme. The aim of this work has been to isolate and characterize such an inhibitor. Blood samples from 105 patients with chronic uremia were collected; plasma was applied to Sephadex G-100 columns and the fraction with the highest inhibiting capacity was identified and purified by subsequent SDS-polyacrylamide gel electrophoresis, followed by electroelution and electroblotting.

Further characterization and kinetic parameter determination of a milk-clotting protease from Mucor bacilliformis.

Further characterization of an aspartyl protease from Mucor bacilliformis with milk-clotting activity was performed. An extinction coefficient, epsilon 278 cm = 1.61 mL/mg/cm, a molecular mass of 35,400 Da and a pI of 5.