Physiological importance of quinoenzymes and the O-quinone family of cofactors.
Physiological importance of quinoenzymes and the O-quinone family of cofactors.
复制标题
DOI：
10.1093/jn/130.4.719
复制
发表时间：
2000-04
期刊：
影响因子：
--
通讯作者：
T. Stites;A. Mitchell;R. Rucker
中科院分区：
文献类型：
--
作者：
T. Stites;A. Mitchell;R. Rucker
来自酪氨酸和色氨酸的邻醌辅因子参与从氧化脱氨基到自由基氧化还原反应的新型生物反应。这些辅因子的形成似乎涉及酪氨酸或色氨酸残基的翻译后修饰。这些修饰导致辅因子，如托帕醌（TPQ）、色氨酸酪氨酸醌（TTQ）、赖氨酸酪氨酰醌（LTQ）或来自金属催化反应的铜络合的半胱氨酰-酪氨酰自由基。吡咯并喹啉醌（PQQ）似乎是由肽基谷氨酸和酪氨酸残基的环化形成的，这些残基源于它们作为前体肽底物的组分的修饰。PQQ，本次审查的主要焦点，引起了相当大的兴趣，因为它存在于食品中，抗氧化性能和作为一种生长促进因子的作用。虽然在动物中没有发现专门利用PQQ的酶，但口服补充纳摩尔量的PQQ可增加B细胞和T细胞对有丝分裂原的反应性，并改善啮齿动物的神经功能和生殖结果。关于TPQ和LTQ，TPQ和LTQ的形成也受到营养状况的影响，特别是膳食铜。对于胺氧化酶中的至少一种赖氨酰氧化酶，酶活性与铜摄入量直接相关。TPQ和LTQ是在通过一种方法掺入铜后产生的，该方法涉及将特定的酪氨酰残基两步氧化为第一肽基多巴，然后是肽基托帕醌以产生活性酶，通常归类为“醌酶”。“有限的关注也支付给TTQ和铜络合的半胱氨酰-酪氨酰自由基，辅助因子重要的真菌和细菌的氧化还原过程。
O-quinone cofactors derived from tyrosine and tryptophan are involved in novel biological reactions that range from oxidative deaminations to free-radical redox reactions. The formation of each of these cofactors appears to involve post-translational modifications of either tyrosine or tryptophan residues. The modifications result in cofactors, such as topaquinone (TPQ), tryptophan tryptophylquinone (TTQ), lysine tyrosylquinone (LTQ) or the copper-complexed cysteinyl-tyrosyl radical from metal-catalyzed reactions. Pyrroloquinoline quinone (PQQ) appears to be formed from the annulation of peptidyl glutamic acid and tyrosine residues stemming from their modification as components of a precursor peptide substrate. PQQ, a primary focus of this review, has invoked considerable interest because of its presence in foods, antioxidant properties and role as a growth-promoting factor. Although no enzymes in animals have been identified that exclusively utilize PQQ, oral supplementation of PQQ in nanomolar amounts increases the responsiveness of B- and T-cells to mitogens and improves neurologic function and reproductive outcome in rodents. Regarding TPQ and LTQ, a case may be made that the formation of TPQ and LTQ is also influenced by nutritional status, specifically dietary copper. For at least one of the amine oxidases, lysyl oxidase, enzymatic activity correlates directly with copper intake. TPQ and LTQ are generated following the incorporation of copper by a process that involves the two-step oxidation of a specified tyrosyl residue to first peptidyl dopa and then peptidyl topaquinone to generate active enzymes, generally classed as "quinoenzymes." Limited attention is also paid to TTQ and the copper-complexed cysteinyl-tyrosyl radical, cofactors important to fungal and bacterial redox processes.