假单胞菌细胞色素c过氧化物酶的结构和功能特征。
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Ellfolk N, Ronnberg M, Osterlund K
假单胞菌细胞色素c过氧化物酶的结构和功能特征。
Biochim Biophys学报。1991年10月11日,1080 (1):68 - 77。
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1657179 (在PubMed]
- 文摘
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假单胞菌细胞色素c过氧化物酶的二级结构(ferrocytochrome c:过氧化氢氧化还原酶,EC 1.11.1.5)一直预测的氨基酸序列建立酶使用Chou-Fasman-type算法。alpha-helicity从而获得的数量和之前的一致结果基于在远紫外圆二色性的测量。前面两个血红素c的半个酶被证明有广泛不同的特征,例如,血红素的氧化还原电位与大约600 mV,不同酶分子并执行不同的功能。beplayapp的结构比较本研究启发观察到的功能差异。第一个血红素多肽链,血红素1在其环境折叠模式通常在遇到细胞色素。在该地区的六配位,然而,深刻的差异。cytochromal蛋氨酸已经取代了赖氨酸的同时降低氧化还原电位从而使peroxidatic活动成为可能。在血红素2,添加了额外的氨基酸残基的过氧化物酶与Rhodospirillum molischianum细胞色素c2 20圈的核心结构。完成后cytochromal褶皱的血红素2组成的一个额外的尾巴25残留有关。这尾巴显示不稳定的二级结构元素,但包含强疏水段表明可能膜接触网站的外在膜蛋白。 Heme 2 is concluded to have a cytochromal function in the molecule. To further elucidate the functional properties of the enzyme, a noncovalent two-fragment complex was produced by specific cleavage of the peroxidase by Pseudomonas elastase. The complex was studied with respect to its properties to the native enzyme. The two-fragment complex of Pseudomonas peroxidase retains the overall conformation of the native enzyme showing, however, no heme-heme interaction. Thus, a comparison of the properties of the native enzyme with those of the two-fragment complex permitted some conclusions to be drawn on the structure of the enzyme as well as the mechanism of heme-heme interaction. From the present results we conclude that the two distal heme surfaces in the peroxidase are oriented toward each other. This structural arrangement allows an inter-heme communication in the enzyme molecule and it also forms the structural basis for the enzyme mechanism. The structural comparisons also give insight into the evolution of an ancestral cytochrome c into an efficient peroxidase that has a versatile control mechanism in heme-heme interaction.