title: Inactivation kinetics of formaldehyde on N-acetyl-β-D-glucosaminidase from Nile tilapia (Oreochromis niloticus).
abstract: Formaldehyde is a widely used sanitizer in aquaculture in China, while the appropriate concentration is not available to be used effectively and without damage to tilapia much less to its reproductive function. N-acetyl-β-D-glucosaminidase (EC 3.2.1.52, NAGase), hydrolyzing the oligomers of N-acetyl-β-D-glucosamine into monomer, is proved to be correlated with reproduction of male animals. In this paper, NAGase from spermary of tilapia was chosen as the material to study the effects of formaldehyde on its activity in order to further investigate the effects of formaldehyde use on tilapia reproduction. The results showed the relationship between the residual enzyme activity and the concentration of formaldehyde was concentration dependent, and the IC50 value was estimated to be 3.2 ± 0.1 %. Appropriate concentration of formaldehyde leaded to competitive reversible inhibition on tilapia NAGase. Moreover, formaldehyde could reduce the thermal and pH stability of the enzyme. The inactivation kinetics of formaldehyde on the enzyme was studied using the kinetic method of substrate reaction. The inactivation model was setup, and the rate constants were determined. The results showed that the inactivation of formaldehyde on tilapia NAGase was a slow, reversible reaction with partially residual activity. The results will give some basis to determine the concentration of formaldehyde used in tilapia culture.
authors.affiliation: University Key Lab for Integrated Chinese Traditional and Western Veterinary Medicine and Animal Healthcare in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
authors.forename: Wei-Ni
authors.initials: WN
authors.lastname: Zhang
authors.forename: Ding-Ping
authors.initials: DP
authors.lastname: Bai
authors.forename: Xin-Yu
authors.initials: XY
authors.lastname: Lin
authors.forename: Qing-Xi
authors.initials: QX
authors.lastname: Chen
authors.forename: Xiao-Hong
authors.initials: XH
authors.lastname: Huang
authors.forename: Yi-Fan
authors.initials: YF
authors.lastname: Huang
mesh_terms: D000118:Acetylglucosaminidase / Q000037:antagonists & inhibitors*; D000818:Animals; D023681:Cichlids / Q000378:metabolism* / Q000502:physiology; D004202:Disinfectants / Q000008:administration & dosage / Q000633:toxicity*; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000633:toxicity; D004795:Enzyme Stability / Q000187:drug effects; D005398:Fisheries; D005557:Formaldehyde / Q000008:administration & dosage / Q000633:toxicity*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008297:Male; D012098:Reproduction / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects / Q000201:enzymology; D013696:Temperature
chemical_list: D004202:Disinfectants; D004791:Enzyme Inhibitors; D005557:Formaldehyde; D000118:Acetylglucosaminidase
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