Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
Arch Biochem Biophys. 2010 Apr 15;496(2):101-8. doi: 10.1016/j.abb.2010.02.004. Epub 2010 Feb 12.
Human arginase I is a binuclear manganese metalloenzyme that catalyzes the hydrolysis of L-arginine to generate L-ornithine and urea. We demonstrate that N-hydroxy-L-arginine (NOHA) binds to this enzyme with K(d)=3.6 microM, and nor-N-hydroxy-L-arginine (nor-NOHA) binds with K(d)=517 nM (surface plasmon resonance) or K(d) approximately 50 nM (isothermal titration calorimetry). Crystals of human arginase I complexed with NOHA and nor-NOHA afford 2.04 and 1.55 A resolution structures, respectively, which are significantly improved in comparison with previously-determined structures of the corresponding complexes with rat arginase I. Higher resolution structures clarify the binding interactions of the inhibitors. Finally, the crystal structure of the complex with L-lysine (K(d)=13 microM) is reported at 1.90 A resolution. This structure confirms the importance of hydrogen bond interactions with inhibitor alpha-carboxylate and alpha-amino groups as key specificity determinants of amino acid recognition in the arginase active site.
人源精氨酸酶 I 是一种双核锰金属酶，能够催化 L-精氨酸水解生成 L-鸟氨酸和尿素。我们证明 N-羟基-L-精氨酸（NOHA）与该酶的结合常数为 Kd=3.6 μM，而 nor-N-羟基-L-精氨酸（nor-NOHA）的结合常数为 Kd=517 nM（表面等离子体共振）或 Kd 约为 50 nM（等温滴定量热法）。与先前测定的大鼠精氨酸酶 I 相应复合物的结构相比，NOHA 和 nor-NOHA 与人源精氨酸酶 I 复合物的晶体分别达到了 2.04 和 1.55Å的分辨率，结构得到了显著改善。更高分辨率的结构阐明了抑制剂的结合相互作用。最后，报道了 L-赖氨酸（Kd=13 μM）复合物的晶体结构，分辨率为 1.90Å。该结构证实了与抑制剂 α-羧基和 α-氨基的氢键相互作用对于精氨酸酶活性部位中氨基酸识别的特异性决定因素的重要性。
