Phatarphekar Abhishek, Buss Jennifer M, Rokita Steven E
Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA.
Mol Biosyst. 2014 Jan;10(1):86-92. doi: 10.1039/c3mb70398c.
Iodide is required for thyroid hormone synthesis in mammals and other vertebrates. The role of both iodide and iodinated tyrosine derivatives is currently unknown in lower organisms, yet the presence of a key enzyme in iodide conservation, iodotyrosine deiodinase (IYD), is suggested by genomic data from a wide range of multicellular organisms as well as some bacteria. A representative set of these genes has now been expressed, and the resulting enzymes all catalyze reductive deiodination of diiodotyrosine with kcat/Km values within a single order of magnitude. This implies a physiological presence of iodotyrosines (or related halotyrosines) and a physiological role for their turnover. At least for Metazoa, IYD should provide a new marker for tracing the evolutionary development of iodinated amino acids as regulatory signals through the tree of life.
碘化物是哺乳动物和其他脊椎动物甲状腺激素合成所必需的。碘化物和碘化酪氨酸衍生物在低等生物中的作用目前尚不清楚，但来自多种多细胞生物以及一些细菌的基因组数据表明，存在一种碘化物保存关键酶——碘酪氨酸脱碘酶（IYD）。现在已经表达了一组具有代表性的这些基因，所产生的酶都催化二碘酪氨酸的还原脱碘反应，其催化常数与米氏常数之比（kcat/Km）值在一个数量级内。这意味着碘酪氨酸（或相关卤代酪氨酸）在生理上的存在以及它们周转的生理作用。至少对于后生动物来说，IYD应该为追踪碘化氨基酸作为调节信号在生命之树中的进化发展提供一个新的标记。
