Structural aspects of the mucor bacilliformis proteinase, a new mwmber of the aspartyl-proteinase family

CLAUDIA MACHALINSKI; MARIA L. PIRPIGNANI; CRISTINA MARINO; ADRIANA MANTEGAZZA; MIRTHA BISCAGLIO DE JIMENEZ BONINO

JOURNAL OF BIOTECHNOLOGY

Año: 2006 vol. 123 p. 443 - 452

0168-1656

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 indicated a high degree of similarity to those of other family members. The protein is monomeric, has two disulfide bridges, is not glycosylated and its spatial arrangement mainly includes the beta structure. A molecular model was built by using the Rhizopus chinensis proteinase structure as the template. Sequence analysis and comparison of our model with bovine chymosin and Mucor pusillus proteinase structures, indicated that the Mucor bacilliformis proteinase is at a similar evolutionary distance on a sequence level; as far as tertiary structure is concerned, the Mucor bacilliformis proteinase superimposes on the bovine chymosin structure better than the Mucor pusillus proteinase does, thus suggesting that this novel proteinase could be utilized as a good milk-clotting enzyme in the dairy industry.