4471
Structure of Bis( methylguanidinium) Monohydrogen Orthophosphate. A Model for the Arginine-Phosphate Interactions at the Active Site of Staphylococcal Nuclease and 0ther Phosphohydrolytic Enzymes’ F. A. Cotton,*2aV. W. Day, E. E. Hazen, Jr.,* 2a S. Larsen,2band S. T. K . Wong Contribution from the Departments of Chemistry, Texas A & M University, College Station, Texas 77843, and University of Nebraska, Lincoln, Nebraska 68508. Received February 6, 1974
Abstract: A compound has been found which provides an excellent model of certain essential features of the arginyl-phosphate interactions in the complex consisting of Staphylococcus nuclease, deoxythymidine 3 ‘,5 ‘-diphosphate, and calcium ion. The crystal structure of this substance, bis(methy1guanidinium)monohydrogen orthophosphate, [CN3NHC(NH2)2]2P030H, has been determibned. Crystal data: space group, Fdd2-C2,I9; unit cell dimensions a = 23.608 (3), b = 24.113 (5), c = 7.917 (1) A ; Z = 16 for the formula unit (C2N3H&HP04;d&d = sin 6
