Specificity of the acid protease from Monascus kaoliang towards the B-chain of oxidized insulin

Characterization of acidic protease from Aspergillus niger BCRC 32720

An acid protease from the broth of a 24 h cultivated Aspergillus niger BCRC 32720 was purified to electrophoretical homogeneity by CM Sepharose FF and Sephacryl S-100 HR chromatographs. The specific activity, purification fold, and yield were 23.29 kU/mg, 2.5, and 24.2%, respectively. Molecular mass (M) and N-terminal amino acid sequence were 47.5 kDa and SKGSAVTT, whereas the pH and temperature optima were at 2.5 and 50 °C, respectively. It was stable at pH 2.0-4.0 or ≤40 °C and activated by Fe(2+) and cysteine, but partially inhibited by phenylmethanesulfonyl fluoride and tosyllysine chloromethyl ketone and highly inhibited by Ag(+), Sn(2+), Fe(3+), Sb(3+), and pepstatin A. It was considered to be an aspartic protease.

Biochemical aspects of red koji and tofuyo prepared using Monascus fungi

Red koji or red mold rice is prepared by growing a genus Monascus on steamed rice. For centuries, it has been used in Asia for the production of fermented foods including red rice wine and fermented tofu. Although red koji is an important source of various hydrolytic enzymes critical for food fermentation, information on the enzymatic properties in red koji has been limited. Hydrolytic enzymes produced by Monascus fungi may play important roles in ripening of tofuyo (Japanese fermented tofu) regarding the chemical and physical properties of the product. This review provides an introduction of red koji, its properties, and the application of hydrolytic enzymes, especially aspartic proteinases and carboxypeptidases from Monascus fungi. We also describe tofuyo and a novel fermented soybean protein food using a microbial action originating from red koji.

Application of an acid proteinase from Monascus purpureus to reduce antigenicity of bovine milk whey protein

An acid proteinase from Monascus purpureus No. 3403, MpuAP, was previously purified and some characterized in our laboratory (Agric Biol Chem 48:1637-1639, 1984). However, further information about this enzyme is lacking. In this study, we investigated MpuAP's comprehensive substrate specificity, storage stability, and prospects for reducing antigenicity of whey proteins for application in the food industry. MpuAP hydrolyzed primarily five peptide bonds, Gln(4)-His(5), His(10)-Leu(11), Ala(14)-Leu(15), Gly(23)-Phe(24) and Phe(24)-Phe(25) in the oxidized insulin B-chain. The lyophilized form of the enzyme was well preserved at 30-40°C for 7 days without stabilizers. To investigate the possibility of reducing the antigenicity of the milk whey protein, enzymatic hydrolysates of the whey protein were evaluated by inhibition ELISA. Out of the three main components of whey protein, casein and α-lactalbumin were efficiently degraded by MpuAP. The sequential reaction of MpuAP and trypsin against the whey protein successfully degraded casein, α-lactalbumin and β-lactoglobulin with the highest degree of hydrolysis. As a result, the hydrolysates obtained by using the MpuAP-trypsin combination showed the lowest antigenicity compared with the single application of pepsin, trypsin or pepsin-trypsin combination. Therefore, the overall result suggested that the storage-stable MpuAP and trypsin combination will be a productive approach for making hypoallergic bovine milk whey protein hydrolysates.

Production, Purification, and Characterization of alpha-Galactosidase from Monascus pilosus

A Monascus pilosus strain was selected for production of intracellular alpha-galactosidase. Optimum conditions for mycelial growth and enzyme induction were determined. Galactose was one of the best enzyme inducers. The enzyme was purified by ammonium sulfate precipitation, gel filtration, and ion exchange chromatography and was demonstrated to be homogeneous by slab gel electrophoresis. The molecular weight of this enzyme, estimated by gel filtration, was about 150,000. The optimum conditions for the enzyme reaction was pH 4.5 to 5.0 at 55 degrees C. The purified enzyme was stable at 55 degrees C or below and in buffer at pH 3 to 8. The activity was inhibited by mercury, silver, and copper ions. The kinetics of this enzyme, with p-nitrophenyl-alpha-d-galactoside as substrate, was determined: K(m) was about 0.8 mM, and V(max) was 39 mumol/min per mg of protein. Enzymatic hydrolysis of melibiose, raffinose, and stachyose was analyzed by thin-layer chromatography.