Department of Chemistry, P.O. Box 30012, Texas A&M University , College Station, Texas 77843-3012, United States.
Biochemistry. 2011 Aug 2;50(30):6589-97. doi: 10.1021/bi200868u. Epub 2011 Jul 6.
Four proteins from NCBI cog1816, previously annotated as adenosine deaminases, have been subjected to structural and functional characterization. Pa0148 (Pseudomonas aeruginosa PAO1), AAur1117 (Arthrobacter aurescens TC1), Sgx9403e, and Sgx9403g have been purified and their substrate profiles determined. Adenosine is not a substrate for any of these enzymes. All of these proteins will deaminate adenine to produce hypoxanthine with k(cat)/K(m) values that exceed 10(5) M(-1) s(-1). These enzymes will also accept 6-chloropurine, 6-methoxypurine, N-6-methyladenine, and 2,6-diaminopurine as alternate substrates. X-ray structures of Pa0148 and AAur1117 have been determined and reveal nearly identical distorted (β/α)(8) barrels with a single zinc ion that is characteristic of members of the amidohydrolase superfamily. Structures of Pa0148 with adenine, 6-chloropurine, and hypoxanthine were also determined, thereby permitting identification of the residues responsible for coordinating the substrate and product.
来自 NCBI cog1816 的 4 种蛋白先前被注释为腺苷脱氨酶，已进行了结构和功能的表征。Pa0148（铜绿假单胞菌 PAO1）、AAur1117（节杆菌 Aur1117）、Sgx9403e 和 Sgx9403g 已被纯化，并确定了它们的底物谱。这些酶都不能作用于腺苷。所有这些蛋白都能将腺嘌呤脱氨产生次黄嘌呤，其 k(cat)/K(m) 值超过 10(5) M(-1) s(-1)。这些酶还可以接受 6-氯嘌呤、6-甲氧基嘌呤、N-6-甲基腺嘌呤和 2,6-二氨基嘌呤作为替代底物。Pa0148 和 AAur1117 的 X 射线结构已被确定，揭示了几乎相同的扭曲（β/α）(8)桶，带有一个锌离子，这是酰胺水解酶超家族成员的特征。还确定了 Pa0148 与腺嘌呤、6-氯嘌呤和次黄嘌呤的复合物结构，从而确定了负责配位底物和产物的残基。
