Studies on the degradation pattern of wheat malt endo-1,4-ß-xylanase on wheat-derived arabinoxylans.

BACKGROUND: Wheat malt endo-1,4-ß-xylanase is a key enzyme for arabinoxylan degradation, but its wheat-derived arabinoxylan degradation pattern is unclear. RESULTS: Water-extractable arabinoxylan (WEAX) of 300-750 kDa and 30-100 kDa were the two components with the highest degradation efficiency of wheat malt endo-1,4-ß-xylanase, followed by > 1000 kDa WEAX, but 100-300 kDa WEAX showed the lowest degradation efficiency. The main enzymatic products were the 5-30 kDa WEAX, which accounted for 57.57%, 68.15%, and 52.28% of WAXH, WAXM, and WAXL products, respectively. The enzymatic efficiency of wheat malt endo-1,4-ß-xylanase was relatively high, and the continuity of enzymatic efficiency was good, especially since the enzymatic reaction was the most intense in 1-3 h. WEAX of > 300 kDa was highly significant and positively correlated with viscosity. In comparison, WEAX of < 30 kDa was highly significant and negatively correlated with viscosity. As the enzymatic degradation proceeded, there were fewer and fewer macromolecular components but more and more small molecule components, and the system viscosity became smaller and smaller. CONCLUSION: In this study, it was found that wheat malt endo-1,4-ß-xylanase degraded preferentially 300-750 kDa and 30-100 kDa WEAX, not in the order of substrate size in a sequential enzymatic degradation. Wheat malt endo-1,4-ß-xylanase was most efficient within 3 h, primarily generating < 30 kDa WEAX ultimately. The main products were highly significantly negatively correlated with the system viscosity, so that the system viscosity gradually decreased as the enzymatic hydrolysis proceeded. © 2024 Society of Chemical Industry.

Degradation of soybean meal proteins by wheat malt endopeptidase and the antioxidant capacity of the enzymolytic products.

This study investigated the hydrolysis effect of the endopeptidase from wheat malt on the soybean meal proteins. The results indicated that the endopeptidase broke the peptide bonds of soybean meal proteins and converted the alcohol- and alkali-soluble proteins into water-soluble and salt-soluble proteins. In addition, wheat malt endopeptidase did not break the disulfide bonds between proteins but affected the conformation of disulfide bonds between substrate protein molecules, which were changed from the gauche-gauche-trans (g-g-t) vibrational mode to the trans-gauche-trans (t-g-t) vibrational mode. Wheat malt endopeptidase exhibited the highest enzymatic activity at 2 h of enzymatic digestion, demonstrating the fastest hydrolytic rate of soybean meal proteins. Compared with the samples before enzymatic hydrolysis, the total alcohol- and alkali-soluble proteins were decreased by 11.89% but the water- and salt-soluble proteins were increased by 11.99%, indicating the hydrolytic effect of endopeptidase. The corresponding water-soluble proteins had molecular weights of 66.4-97.2, 29-44.3, and 20.1 kDa, while the salt-soluble proteins had molecular weights of 44.3-66.4, 29-44.3, and 20.1 kDa, respectively. The degree of enzymatic hydrolysis of soybean meal reached the maximum at 8 h. The newly created proteins exhibited significantly antioxidant properties, which were inversely related to the molecular weight. Proteins with molecular weight <3 kDa had the highest antioxidant performance with an antioxidant capacity of 1.72 ± 0.03 mM, hydroxyl radical scavenging rate of 98.04%, and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] radical scavenging capacity of 0.44 ± 0.04 mM.