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This is the first of a series of four articles in which the chemical, enzymological, and crystallographic work on Ribonucleate (deoxyribonucleate)-3′-nucleotidohydrolase, EC 3.1.4.7, (Staphylococcal nuclease, Micrococcal nuclease) will be reviewed and correlated. This article discusses the purification of the enzyme and its general physical and(More)
The structure of the staphylococcal nuclease (EC 3.1.4.7)-thymidine 3',5'-bisphosphate-Ca(2+) (enzyme-inhibitor) complex has been extended to 1.5-A resolution by using much additional data and a phase refinement scheme based on an electron-density map modification procedure. By correlating this structure with the known properties of the enzyme, a mechanism(More)
SUMMARY Two isomorphously substituted derivatives of the nuclease-Ca2+-thymidine 3',5'-diphosphate complex have been prepared and used in an x-ray crystallographic study of the molecular structure. In one case, 5-iododeoxyuridine 3',5'-diphosphate was used in place of thymidine 3',5'-diphosphate (a net replacement of CHB by I), and, in the other, BaZf was(More)
This is the third in a series of four articles in which the chemical, enzymological and crystallographic work on Ribonucleate (deoxribonucleate)-3′-nucleotidohydrolase, EC 3.1.4.4 (staphylococcal nuclease, micrococcal nuclease) will be reviewed and correlated. This article describes the structure of the nuclease and of a nuclease-inhibitor complex as(More)
The P-O-ethyl ester of cAMP has been synthesized, its inhibition of solid and ascites tumors studied, and its pattern of urinary excretion followed. Et-cAMP is more effective than cAMP against solid sarcoma 180 in mice and against Ehrlich ascites carcinoma cells in tissue culture. The urinary excretion pattern of injected E-t-cAMP suggests that about(More)
Single-molecule transistors incorporating trimetal molecules of Cu(3)(dpa)(4)Cl(2) and Ni(3)(dpa)(4)Cl(2) (dpa = 2,2'-dipyridylamide) have been fabricated. Conductance is measured as a function of bias and gate voltages at low temperature, showing single-electron tunneling behavior through the molecules. Additional structures corresponding to the(More)
Independent 4 A electron density maps calculated for the extracellular nuclease of Staphylococcus aureus (based on data from three heavy-atom derivatives) and for a nuclease-thymidine-3',5'-diphosphate-calcium ion complex (based on a single isomorphous derivative) show about 60 per cent of the chain resolved, including 3(1/2) turns of helix. The pyrimidine(More)
Supramolecular chemistry is today a major thrust area, a significant part of which is based on the use of metal atoms or ions as key elements in promoting the assembly of and dictating the main structural features of the supramolecular products. Most of the work has been done with single metal atoms or ions in this role, but considerable success has already(More)