大頭紅蝦酪胺酸酶之兩種異構酶動力學機制

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Title:	大頭紅蝦酪胺酸酶之兩種異構酶動力學機制 Kinetic Mechanism of Two Isozymes of Bighead Shrimp Tyrosinase
Authors:	蕭介夫朱惠鈴
Contributors:	中央研究院植物研究所國立臺灣海洋大學水產食品科學研究所
Keywords:	Shrimp Solenocera melantho Tyrosinase Isozyme Kinetics Hysteresis Suicide inactivation
Date:	1990
Issue Date:	2011-03-29 14:27:05 (UTC+8)
Abstract:	以DOPA為基質，大頭紅蝦兩種酩胺酸酶同功異構酶Fl及F2均表現Michaelis-Menten動力學， Fl同功異構酶之Km為0.356 mM, F2同功異構酶之Km為1.395 mM。以酩胺酸為基質， Fl表現出歇斯底里型動力學(hysteretic kinetics)，而遲滯期(lag time)深受酪胺酸濃度、F1酵素濃度及pH值影響，其動力學反應機制是屬於聚合一解離作用之歇斯底里型反應(association-dissociation hysteresis)。以兒茶酚(catechol)為基質時， Fl表現出自殺型動力學反應(suicide kinetics)，酵素失活時間與兒苯酚濃度有關，其動力學機制是屬於多基質機制(multisubstrate mechanism)。同樣以兒苯酚為基質F2表現出歇斯底里型動力學反應，而過渡期(transition time)受兒茶酚濃度影響，其動力學反應機制是屬於ligand-induced isomerization之歇斯底里型反應。 Both tyrosinase isozymes Fl and F2 exhibited Michaelis-Menten kinetic with DOPA as substrate. The Km values of the Fl and F2 were 0.356mM and 1.395mM respectively. Fl exhibited suicide reaction behavior while F2 showed hysteresis with catechol as substrate. The kinetic analysis suggested that the Fl and F2 were multisubstrate suicide mechanism and the ligand-induced isomerization hysteresis mechanism respectively. Fl also showed hysteretic reaction kinetics when tyrsoine was used as substrate. Lag time was afected by the concentration oF tyrosine, the enzyme concentration and pH. The kinetic analysis suggested that it was the association-dissociation hysteresis mechanism.
Relation:	嘉南學報 16期 : 頁A31-A42 轉載中國農業化學會誌 27(4) : p.429-440 (1989)
Appears in Collections:	[Chna Nan Annual Bulletin] Vol.16 (1990) [Dept. of Food Science & Technology] Periodical Articles

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