Iodide oxidation and iodine reduction by horseradish peroxodase in the presence of EDTA: the superoxide effect.

ASIA unversity > 醫學暨健康學院 > 生物科技學系 > 期刊論文 > Item 310904400/16059

jsp.display-item.identifier=請使用永久網址來引用或連結此文件: http://asiair.asia.edu.tw/ir/handle/310904400/16059

题名:	Iodide oxidation and iodine reduction by horseradish peroxodase in the presence of EDTA: the superoxide effect.
作者:	張竣維;Hebron, C.Chang
贡献者:	生物科技學系
日期:	2001
上传时间:	2012-11-23 09:08:04 (UTC+0)
摘要:	Ethylenediaminetetraacetic acid (EDTA) is an inhibitor of iodide (I-) oxidation that is catalyzed by horseradish peroxidase (HRP). HRP-mediated iodine (I2) reduction and triiodide (I3+) disappearance occur in the presence of this inhibitor. It is interesting that in the presence of EDTA, HRP produces superoxide radical, a reactive oxygen species that is required for iodine reduction. Substitution of potassium superoxide (KO2) or a biochemical superoxide generating system (xanthine/xanthine oxidase) for HRP and H2O2 in the reaction mixture also can reduce iodine to iodide. Thus, iodine reduction mediated by HRP occurs because HRP is able to mediate the formation of superoxide in the presence of EDTA and H2O2. Although superoxide is able to mediate iodine reduction directly, other competing reactions appear to be more important. For example, high concentrations (mM range) of EDTA are required for efficient iodine reduction in this system. Under such conditions, the concentration (microM range) of contaminating EDTA-Fe(III) becomes catalytically important. In the presence of superoxide, EDTA-Fe(III) is reduced to EDTA-Fe(II), which is able to reduce iodine and form triiodide rapidly. Also of importance is the fact that EDTA-Fe(II) reacts with hydrogen peroxide to form hydroxyl radical. Hydroxyl radical involvement is supported by the fact that a wide variety of hydroxyl radical (OH) scavengers can inhibit HRP dependent iodine reduction in the presence of EDTA and hydrogen peroxide.
關聯:	JOURNAL OF BIOMEDICAL SCIENCE;25(2):82-9.
显示于类别:	[生物科技學系] 期刊論文

文件中的档案:

没有与此文件相关的档案.

在ASIAIR中所有的数据项都受到原著作权保护.

数据加载中.....