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Contribution of Cathepsin L to Autolysis of Sea Cucumber Stichopus japonicus Intestines

Yan, Jia-Nan, Guo, Xiao-Kun, Tang, Yue, Li, Ao-Ting, Zhu, Zhi-Mo, Chai, Xiao-Qian, Duan, Xiu-Hong, Wu, Hai-Tao
Journal of aquatic food product technology 2019 v.28 no.2 pp. 233-240
Apostichopus japonicus, autolysis, butanes, cathepsin L, gene expression, gene expression regulation, intestines, iodoacetic acid, messenger RNA, oligopeptides, pH, polyacrylamide gel electrophoresis, protein degradation, proteolysis, reverse transcriptase polymerase chain reaction, soybeans, trichloroacetic acid, trypsin inhibitors, ultraviolet radiation
In order to provide the fundamental basis for control and application of sea cucumber autolysis, the contribution of cathepsin L to intestinal proteolysis in sea cucumber (Stichopus japonicus) was investigated. Cathepsin L mRNA expression was significantly up-regulated by 1.80 ± 0.44-fold with ultraviolet irradiation (p< 0.05). According to the protein pattern identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and determination of the release of trichloroacetic acid (TCA)-soluble oligopeptide, high intestinal protein degradation was observed at pH 4.4 and 48°C. Intestinal protein proteolysis was strongly inhibited by cathepsin L inhibitors, including trans-epoxysuccinyl-L-leucyl-amido (4-guani-dino)butane (E-64), iodoacetic acid (IA), and antipain (AP). These results imply that cathepsin L is involved in intestinal autolysis in the sea cucumber S. japonicus. Abbreviations: TCA: trichloroacetic acid; Z-Phe-Arg-AMC: Z-Phe-Arg-7-amido-4-methylcou-marin; IA: iodoacetic acid; E-64: trans-epoxysuccinyl-L-leucyl-amido (4-guanidino) butane; AP: antipain; SBTI: soybean trypsin inhibitor; SDS-PAGE: sodium dodecyl sulfate polyacrylamide gel electrophoresis; RT-PCR: reverse transcription-polymerase chain reaction