Pyridoxal-5'-phosphate-dependent transaminases of fold type IV (class IV) are promising enzymes for (R)-selective amination of organic compounds. Transaminases of fold type IV exhibit either strict (R)-selectivity or (S)-selectivity that is implemented within geometrically similar active sites of different amino acid compositions. Based on substrate specificity, class IV comprises three large families of transaminases: (S)-selective branched-chain L-amino acid aminotransferases and (R)-selective D-amino acid aminotransferases and (R)-amine:pyruvate transaminases. In this review, we aim to analyze the substrate profiles and correlations between the substrate specificity and organization of the active site in transaminases from these structurally related families. New transaminases with an expanded substrate specificity are also discussed. An analysis of the structural features of substrate binding and comparisons of structural determinants of chiral discrimination between members of the class IV transaminases could be helpful in identifying new biocatalytically relevant enzymes as well as rational protein engineering.

中文翻译：

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对PLP折叠IV型转氨酶底物特异性的结构见解。

折叠类型IV（类IV）的吡咯醛-5'-磷酸盐依赖性转氨酶是用于有机化合物的（R）选择性胺化的有前途的酶。折叠类型IV的转氨酶显示出严格的（R）-选择性或（S）-选择性，其在不同氨基酸组成的几何相似的活性位点内实现。基于底物特异性，IV类包含三个大家族的转氨酶：（S）-选择性支链L-氨基酸氨基转移酶和（R）-选择性D-氨基酸氨基转移酶和（R）-胺：丙酮酸转氨酶。在这篇综述中，我们旨在分析来自这些结构相关家族的转氨酶中底物谱和底物特异性与活性位点组织之间的相关性。还讨论了具有扩大的底物特异性的新型转氨酶。