Cytochrome c Peroxidase-Like Activity of Chemically Modified Myoglobins

化学修饰肌红蛋白的细胞色素 c 过氧化物酶样活性

基本信息

批准号：
10640546
负责人：
TSUKAHARA Keiichi
金额：
$ 2.05万
依托单位：
Nara Women's University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Horse heart metmyoglobin (metMb), whose lysine residues were modified with diethylenetriaminepentaacetic acid (DTPA), was characterized by a MALDI-TOF mass spectroscopy, an amino-acid sequence analysis, and UV-Vis and CD spectroscopies. Kinetics of the oxidation of the reduced cytochrome c (cyt c(II)) wit hydrogen peroxide catalyzed by metMb(DTPA)ィイD2nィエD2(n = 1, 2, 4, and 5) was investigated spectrophotometrically compared with native metMb. The modified metMb(DTPA)ィイD2nィエD2 showed the cytochrome c peroxidase-like activity more efficiently than the native metMb (metMb(DTPA)ィイD25ィエD2 > metMb(DTPA)ィイD24ィエD2 > metMb(DTPA)ィイD22ィエD2 > metMbDTPA 【greater than or equal】 native metMb). The native metMb does not bind cyt c(II), but metMb(DTPA)ィイD2nィエD2 can bind cyt c(II) with an anionic patch where DTPA anions are liked to the Lys residue(s) on the surface of metMb. The formation of the diprotein complex of metMb(DTPA)ィイD2nィエD2 with cyt c(II) accelerates the electron-transfer (ET) reaction fro … More m cyt c(II) to ferrylMb. An intermediate ferrylMb-protein radical was also detected by an ESR measurement ; it might be a Tyr146 radical. The photoinduced ET reaction between cyt c(III) and zinc-substituted myoglobin modified with DTPA ions, was reexamined. The first-order rate constant for the concentrations of cyt c(III), suggesting ZnMb(DTPA)ィイD2nィエD2(n = 2, 4, and 5) was saturated with increasing the concentrations of cyt c(III), suggesting that the ET quenching occurs within a diprotein complex. The formation constant for the diprotein complex increased with increasing the number of DTPA ions on the lysine residues of myoglobin and decreased with increasing ionic strength, indicating that cyt c(III) interacts with the DTPA anionic patch. The intermolecular ET rate constants in the diprotein complex increased with increasing the number of DTPA ions and decreased with increasing ionic strength. It is suggested that a gating occurs by fluctuation in the configuration of a diprotein complex. Less

马心Metmyoglobin（METMB）-TOF质谱，氨基酸序列分析以及UV-VIS和CD光谱。 1、2、4和5）与天然METMB进行比较。 D2> MetMBDTPA [大于或相等）。（DTPA）i）通过ESR测量结果检测到电子转移（ET）反应。用DTPA离子修饰，重新定向了Cyt C（III）的浓度的一阶速率，随着Cyt C（III）的增加，ET淬火发生在二倍蛋白复合物中。 Diprotex增加了肌红蛋白赖氨酸残基上的DTPA离子数量，并随着强度的增加而减小，表明Cyt C（III）与DTPA阴离子斑块相互作用。 ND随着离子强度的增加而降低