Datensatz

Zusammenfassung

1Procedures are given for the syntheses of α, ω-dinucleoside 5′-polyphosphates as inhibitors of adenylate Kinases. The following order for the ability of inhibiting pig muscle adenylate kinase was observed: Ap5A>1: N6 -etheno-Ap5A>Ap6A>Gp5A>Up5A. The synthesis of adenosine tetraphosphate, the starting material for Ap5A, is also described. 2One molecule of pig muscle adenylate kinase binds one molecule of Ap5A. The difference spectrum of Ap5A -adenylate kinase with its maximum of 5050 M−1 -cm−1 at 271 nm, as well as the fluorescence properties of 1: N6 -etheno-Ap5A can be used for kinetic and binding studies. 3The specific binding of the negatively charged Ap5A was exploited in the preparation of human muscle adenylate kinase. The enzyme was purified to homogeneity with an overall yield of 65%, the absolute value being 70 mg per kg of muscle. 4The effect of Ap5A on adenylate kinase in extracts of various cells and cell organelles was tested. A ratio of 1:50 (mol/mol) for Ap5A to other nucleotides was used for suppressing the adenylate kinase activity in extracts of mammalian and insect skeletal muscle, of human erythrocytes and of Staphylococcus aureus. A ratio of 1:5 was found to be necessary for the adenylate kinase from tobacco leaves and spinach chloroplasts, and a ratio of 2:1 was needed for suppressing the adenylate kinase from bovine liver mitochondria, human kidney homogenate and from Excherichia coli. Ap5A appears not to lbe metabolized in any of the above extracts. These results indicate that Ap5A can be used for evaluating the contribution of adenylate kinase to the production of ATP from ADP in energytransducing systems. 5Contaminating adenylate kinase can be inhibited by a concentration of Ap5A which does not interfere in the study of many (phospho)kinase and ATPases. The applications of Ap5A in the assay for nucleoside diphosphokinase and in the study of mechanical and biochemical properties of contractile proteins are representative examples. The use of Ap5A makes it possible to study the effect of ADP per se in such systems. 6Sepharose-bound Ap5A was used for removing traces of adenylate kinase from samples of myosin and creatine kinase. 7In the presence of Ap5A the activity of creatine kinase was measured in hemolytic serum of venous blood, in plasma of capillary blood and in samples of whole blood after complete hemolysis had been induced. The clinical significance of these findings are shown for cases of myocardial infarction and muscular dystrophy.