title: Inactivation kinetics of β-N-acetyl-D-glucosaminidase from green crab (Scylla serrata) by guanidinium chloride.
abstract: β-N-acetyl-D-glucosaminidase (NAGase) is a major member in chitinolytic enzymes system, which plays an important role in the hatching and molting processes of marine organism. The effects of guanidinium chloride (GuHCl) on the activity of NAGase from green crab (Scylla serrata) were investigated in this study. In results, GuHCl causes reversible inactivation of the enzyme at below 0.8 M concentrations, and the IC50 is estimated to be 0.15 M. The relationship between the enzyme activity and conformation was charaterized by monitoring the change of protein fluorescence spectra. With increasing GuHCl concentration, the fluorescence intensity of the enzyme distinctly decreases , and the maximal emission peaks appear red-shifted (from 338 nm to 343 nm). The enzyme inactivation precedes conformational changes, indicating that the enzyme active site is more flexible than the whole enzyme molecule. The result of the kinetics of inactivation shows that the value of k(+0) is larger than that of k(+0)'. It suggests that the substrate could protect the enzyme to a certain extent during guanidine denaturation. Our results provide important new insights in marine organism culture, especially in crustacean growth.
authors.affiliation: State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen 361005, Fujian, P R China.
authors.forename: Ji-Ping
authors.initials: JP
authors.lastname: Zhang
authors.forename: Bo
authors.initials: B
authors.lastname: Leng
authors.forename: Qian-Sheng
authors.initials: QS
authors.lastname: Huang
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: Yan
authors.forename: Xuan
authors.initials: X
authors.lastname: Liu
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.forename: Qing-Xi
authors.initials: QX
authors.lastname: Chen
mesh_terms: D000118:Acetylglucosaminidase / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D003386:Brachyura / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D019791:Guanidine / Q000494:pharmacology*; D007700:Kinetics; D011489:Protein Denaturation / Q000187:drug effects; D013050:Spectrometry, Fluorescence
chemical_list: D000118:Acetylglucosaminidase; D019791:Guanidine