CATALASE-PEROXIDASE CATALYSIS IN ANTIBIOTIC ACTIVATION

描述：（改编自申请人的摘要） 我的研究目的是解释分枝杆菌的催化功能 结核过氧化氢酶-过氧化物酶，一种血红素酶，在活化 抗分枝杆菌抗生素异烟肼（异烟酸 酰肼）。 具体目标包括识别近端 过氧化氢酶-过氧化物酶中血红素铁的配体，自旋的表征 血红素铁在静息酶中的状态和配位数， 高价酶中间体的鉴定和动力学分析 这些中间体与异烟肼的反应。 特殊 感兴趣的是氧亚铁过氧化氢酶的潜在催化能力， 过氧化物酶和过氧亚硝酸盐激活酶的潜力。 选择的氨基酸残基在催化机制中的作用， 将通过检查 两种突变过氧化氢酶-过氧化物酶的性质， 临床分离的异烟肼耐药M.结核菌株 抑制另一个M。结核酶，一种脂肪酰基烯酰基 还原酶（inhA蛋白）被认为是药物作用的靶点， 异烟肼激活过氧化氢酶-过氧化物酶，也将进行研究。 其他目的解决Mn（II）-过氧化物酶活性的过氧化氢酶-过氧化物酶 被认为是重要的，因为Mn（III）是有效的单电子 异烟肼的氧化剂。 光学停流技术 光谱、共振拉曼和电子顺磁共振 将在实验方案中应用光谱学。 的 拟议研究的结果将促进详细了解 目前使用的一线抗生素治疗 结核

DESCRIPTION: (adapted from applicant's abstract) The major role of the propose research is to explain the catalytic function of Mycobacterium Tuberculosis catalase-peroxidase, a heme-enzyme, in the activation of the antimycobacterial antibiotic, isoniazid (isonicotinic acid hydrazide). The specific aims include identification of the proximal ligand to heme iron in catalase-peroxidase, characterization of the spin state and coordination number of the heme iron in the resting enzyme, identification of hypervalent enzyme intermediates, and kinetic analysis of the reaction of these intermediates with isoniazid. Of special interest is the potential catalytic competence of oxy-ferrous catalase- peroxidase, and the potential for peroxynitrite to activate the enzyme. The role of selected amino acid residues in the catalytic mechanism an in isoniazid binding will be evaluated through examination of the properties of two mutant catalase-peroxidase enzymes identified from clinically isolated, isoniazid resistant M. tuberculosis strains. Inhibition of another M. tuberculosis enzyme, a fatty acyl enoyl reductase (the inhA protein) thought to be a target of drug action, by isoniazid activated catalase-peroxidase, will also be investigated. Other aims address the Mn(II)-peroxidase activity of catalase-peroxidase considered important because Mn(III) is an efficient single electron oxidant of isoniazid. The techniques of optical stopped-flow spectroscopy, resonance Raman, and electron paramagnetic resonance spectroscopies will be applied in the experimental protocols. The results of the proposed studies will advance a detailed understanding of the action of a first line antibiotic in current use to treat tuberculosis.