Kinetic Analysis of Oxygen Utilization during Cofactor Biogenesis in a Copper-Containing Amine Oxidase from Yeast

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• 作者：Benjamin Schwartz ; Joanne E. Dove ; and Judith P. Klinman
• 刊名：Biochemistry
• 出版年：2000
• 出版时间：April 4, 2000
• 年：2000
• 卷：39
• 期：13
• 页码：3699 - 3707
• 全文大小：216K
• 年卷期：v.39,no.13(April 4, 2000)
• ISSN：1520-4995

文摘

A detailed kinetic analysis of oxygen consumption during TPQ biogenesis has been carriedout on a yeast copper amine oxidase. O₂ is consumed in a single, exponential phase, the rate of whichresponds linearly to dissolved oxygen concentration. This behavior is observed up to conditions ofmaximally obtainable oxygen concentrations. In contrast, no viscosity effect is observed on rate, implicatinga high K_m for O₂. Binding of oxygen appears to occur faster than its consumption and to result indisplacement of the precursor tyrosine onto copper to form a charge-transfer species, described in the thepreceding paper of this issue [Dove, J. E., Schwartz, B., Williams, N. K., and Klinman, J. P. (2000)Biochemistry 39, 3690-3698). Reaction between this intermediate and O₂ is proposed to occur in a rate-limiting step, and to proceed more rapidly when the tyrosine is deprotonated. This rate-limiting step incofactor biogenesis does not display a solvent isotope effect and is, thus, uncoupled from proton transfer.Comparisons are drawn between the proposed biogenesis mechanism and that for the oxidation of reducedcofactor during catalytic turnover in the mature enzyme.