Identification and magnetic immobilization of a pyrophilous aspartic protease from Antarctic psychrophilic fungus

• Published in: Journal of food biochemistry 2018-12, Vol.42 (6), p.e12691-n/a
• Main Authors: Gao, Bei, He, Lei, Wei, Dongzhi, Zhang, Lujia
• Format: Article
• Language: English
• Subjects: aspartic protease; bond specificity; cheese‐making; magnetic immobilization
• ISSN: 0145-8884; 1745-4514
• DOI: 10.1111/jfbc.12691

Aspartic protease is a versatile protease used in the food processing industry. A novel aspartic protease gene (P10) was cloned from an Antarctic psychrophilic fungus Geomyces pannorum and successfully expressed in Aspergillus oryzae when cultured at 20°C. However, purified P10 exhibited optimal activity at 60°C and retained approximately 80% activity at 50–70°C. The Km and Vmax values for this protease toward BSA were 1.01 mg/ml and 4.4 × 10−2 mg/(ml min), respectively, with a specific activity of 585 U/mg. P10 showed broad substrate specificity, with an increased affinity for hydrolyzing κ‐casein than for α‐casein and β‐casein, indicating a potential value for cheese‐making. P10 also presented wide peptide bond specificity toward the oxidized insulin B chain with high affinity for the C‐terminus. Furthermore, P10 was immobilized on iron oxide nanoparticles, wherein it displayed improved thermostability and pH tolerance. These results provide novel insights into psychrophilic fungal enzymes, suggesting P10 as a potential biocatalyst. Practical applications Aspartic protease is one of the most versatile enzymes in food processing. Owing to the increasing demand in cheese products, microbial aspartic proteases are used as beneficial complements for animal‐derived milk coagulant. In this study, a novel aspartic protease (P10) was well studied. Its potential application in cheese‐making and magnetic immobilization were investigated. Our results potentially provide novel insights into psychrophilic fungal enzymes and suggest their application in the food industry.