中文摘要：

采用特异性荧光底物法检测海参体壁组织蛋白酶K（CTSK）的酶学性质并初步探讨其对海参自溶的影响。结果表明：CTSK的最适pH为5.0，最适温度为50℃，在20~40℃之间酶活力稳定性较好；Zn^2＋、Fe^2＋、Fe^3＋、Cu^2＋均对CTSK产生一定抑制作用，抑制率均超过60%；而Ca^2＋和Mn^2＋对其活性影响不大，Mg^2＋可增强该酶活性、CA-074、Z-Leu-Leu-Leu-H（ZLLL）、碘乙酸、E-64、抗痛素、PMSF对CTSK的抑制率均在85%以上，EDTA和1，10-菲啰啉对该酶的抑制率分别为39.7%和16%，而DTT和L-Cys可将该酶活力分别提高至127.46%和238.3%。在海参匀浆物中分别加入特异性抑制剂CA-074和ZLLL，25℃水浴加热使其发生自溶，并通过SDS-PAGE检测CTSK对海参蛋白降解的影响。结果显示ZLLL能够在一定程度上抑制海参蛋白的降解。CTSK是一种巯基氨基酸含量较高的半胱氨酸蛋白酶，具有一定的金属离子依赖性，但又易被多种金属离子抑制；CTSK有可能直接参与海参自溶过程中蛋白质的降解。

英文摘要：

Characteristics of cathepsin K （CTSK） in the body wall of sea cucumber and its influence on autolysis was studied.Specific fluorescence substrate （Z-Gly-Pro-Arg-MCA） was used to investigate some properties of CTSK.The results showed that：Maximum activity of CTSK was observed at pH5.0 and 50℃.Its activity kept stable at 20-40℃ and was inhibited by Zn^2＋,Fe^2＋,Fe^3＋ and Cu^2＋ with an inhibition rate more than 60%.Ca^2＋ and Mn^2＋ had no effect on its activity,however,Mg^2＋ enhanced the activity.CA-074,Z-Leu-Leu-Leu-H（ZLLL）,iodoacetate,E-64,antipain,PMSF inhibited CTSK activity with an inhibitory rate over 85%.EDTA and 1,10-phenanthroline showed inhibition effect on CTSK at an inhibition rate of 16% and 39.7%,respectively.Compared with the control group,DTT and L-Cys promoted the activity up to a high percentage of 127.46% and 238.3%,respectively.CA-074 and ZLLL were then added into sea cucumber meat homogenate respectively,the mixture was incubated at 25℃ for the meat to develop autolysis.The effect of CA-074 and ZLLL on protein degradation of sea cucumber was examined by SDS-PAGE.The results indicated that ZLLL inhibited the degradation of protein to a certain degree.Sea cucumber CTSK was a typical cysteine protease with high content of sulphur amino acid,ion dependent and sensitive to many metal ions.It might directly participate in the protein degradation during autolysis of sea cucumber.