Differential Activation of a Latent Polyphenol Oxidase Mediated by Sodium Dodecyl Sulfate

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• 作者：Fernando Gandí ; a-Herrero ; Mercedes Jimé ; nez-Atié ; nzar ; Juana Cabanes ; Francisco Garcí ; a-Carmona ; and Josefa Escribano
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2005
• 出版时间：August 24, 2005
• 年：2005
• 卷：53
• 期：17
• 页码：6825 - 6830
• 全文大小：92K
• 年卷期：v.53,no.17(August 24, 2005)
• ISSN：1520-5118

文摘

A kinetic study of the activity of soluble and membrane-bound latent polyphenol oxidase (PPO)extracted from beet root (Beta vulgaris) was carried out. For the first time, two types of behavior(hyperbolic and sigmoid) are reported in the same enzyme for PPO activation by the surfactant sodiumdodecyl sulfate (SDS), depending on substrate nature. A kinetic model based on cooperative systemsis developed to describe the activation effect of SDS, enabling the determination of the number ofsurfactant molecules binding to the enzyme in the activation process. The results indicate that theactive site of the enzyme is not affected by SDS and that a stepwise conformational change favorsthe access of hydrophobic substrates compared to hydrophilic ones. Differential activation of PPOmediated by SDS may be of relevance in the control of PPO activity since the enzyme is able toexpress activity toward a specific substrate while remaining latent to others.Keywords: Polyphenol oxidase; tyrosinase; latency; activation; sodium dodecyl sulfate; Beta vulgaris;betalains