Activation of the endogenous acid protease in the head of Litopenaeus vannamei induced by UV‐C irradiation

Abstract

SummaryPrevious studies have found that UV‐C irradiation activated endogenous acid protease (EAP) in shrimp heads. Aiming at understanding the effect of UV‐C irradiation on the activation of EAP and improving the utilisation of EAP, the effect of UV‐C irradiation on the enzymatic properties and conformation of EAP was investigated. The enzymatic properties of EAP were unaltered after UV‐C irradiation, and the optimum pH, temperature, and NaCl concentration were 3, 60°C, and 0.5 mol/L, respectively. Ca2+ and Mg2+ activated the enzyme. The molecular weight of the purified endogenous acid protease (P‐EAP) was 32 kDa. UV–Vis, FTIR, circular dichroism, and fluorescence spectroscopy indicated that the increase in enzyme activity by UV‐C irradiation was related to an increase in tryptophan and hydrogen bonding, implying that it may be the change in the spatial structure of the protein that caused the activation of the enzyme. Results revealed that UV‐C irradiation can be used to activate proteases and provide a reference for enhancing the enzymatic activity of other enzymes from shrimp heads.