Inhibition of human arginase I by substrate and product analogues.
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.
Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
Luigi
L
Di Costanzo
Monica
M
Ilies
Katherine J
KJ
Thorn
David W
DW
Christianson
D001119:Arginase / Q000037:antagonists & inhibitors*; D001120:Arginine / Q000031:analogs & derivatives* / Q000737:chemistry; D004789:Enzyme Activation; D006801:Humans; D011485:Protein Binding; D013379:Substrate Specificity
C404735:N(omega)-hydroxynorarginine; D001120:Arginine; D001119:Arginase