Active Site Binding Is Not Sufficient for Reductive Deiodination by Iodotyrosine Deiodinase.

ABSTRACT: The minimal requirements for substrate recognition and turnover by iodotyrosine deiodinase were examined to learn the basis for its catalytic specificity. This enzyme is crucial for iodide homeostasis and the generation of thyroid hormone in chordates. 2-Iodophenol binds only very weakly to the human enzyme and is dehalogenated with a k_cat/K_m that is more than 4 orders of magnitude lower than that for iodotyrosine. This discrimination likely protects against a futile cycle of iodinating and deiodinating precursors of thyroid hormone biosynthesis. Surprisingly, a very similar catalytic selectivity was expressed by a bacterial homologue from Haliscomenobacter hydrossis. In this example, discrimination was not based on affinity since 4-cyano-2-iodophenol bound to the bac

SUBMITTER: Ingavat N 

PROVIDER: S-EPMC5330855 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature