The Role of Microbial Aspartic Protease Enzyme in Food and Beverage Industries

Table 1

The characteristics of four types of protease [6].

Properties	EC number	Molar mass range (kDa)	pH optimum	Temperature optimum	Metal requirement(s)	Active amino acid(s)	Major inhibitor(s)	Major sources
Aspartyl or carboxyl protease	3.4.23	30–45	3–5	40–55	Ca^2+	Aspartate or cysteine	Pepstatin	Aspergillus, Mucor, Endothia, Rhizopus, Pencillium, Neurospora, animal tissue (stomach)
Cysteine or thiol protease	3.4.22	34–35	2–3	40–55	—	Aspartate or cysteine	Iodoacetamide, p-CMB	Aspergillus, stem of pineapple (Ananas comosus), latex of fig tree (Ficus sp), papaya (Carica papaya), Streptococcus, Clostridium
Metalloprotease	3.4.24	19–37	5–7	65–85	Zn^2+, Ca^2+	Phenylalanine or leucine	Chelating agents such as EDTA and EGTA	Bacillus, Aspergillus, Pencillium, Pseudomonas, Streptomyces
Serine protease	3.4.21	18–35	6–11	50–70	Ca^2+	Serine, histidine, and aspartate	PMSF, DIFP, EDTA, soybean trypsin inhibitor, phosphate buffers, indole, phenol, and triamino acetic acid	Bacillus, Aspergillus, animal tissue (gut), Tritirachium album (thermostable)