1. 5-Phosphoribosyl 1-methylenediphosphonate was isolated after reaction of ribose 5-phosphate and O-adenylyl methylenediphosphonate with 5-phosphoribosyl pyrophosphate synthetase from Ehrlich ascites-tumour cells. 2. The analogue reacted with adenine phosphoribosyltransferase, hypoxanthine phosphoribosyltransferase and nicotinamide phosphoribosyltransferase [K(m) (analogue)/K(m) (5-phosphoribo...

1. The activity of pig heart pyruvate dehydrogenase kinase was assayed by the incorporation of [(32)P]phosphate from [gamma-(32)P]ATP into the dehydrogenase complex. There was a very close correlation between this incorporation and the loss of pyruvate dehydrogenase activity with all preparations studied. 2. Nucleoside triphosphates other than ATP (at 100mum) and cyclic 3':5'-nucleotides (at 10...

Heart J 10: 1025, 1934 32. Prinzmetal M, Kennamer R, Maxwell M: Studies on the mechanism of ventricular activation. VIII. The genesis of the coronary QS wave in through-and-through infarction. Am J Med 17: 610, 1954 33. Cowley MJ, Mantle JA, Rogers WJ, Russell RG, Rackley CE, Logic JR: Technetium 99m stannous pyrophosphate myocardial scintigraphy. Reliability and limitations in assessment of ac...

The hypothesis that anterior ST segment depression represents concomitant posterior infarction was tested in 49 patients admitted with a first transmural inferior myocardial infarction. Anterior ST depression was defined as 0.1 mV or more ST depression in leads V1, V2 or V3 on an electrocardiogram recorded within 18 hours of infarction. Serial vectorcardiograms and technetium pyrophosphate scan...

When pyrophosphate has been found to influence an enzymatic reaction, its action is usually indirect, that is as a chelator of free essential metal ions rather than directly on the protein catalyst. However, it appears that the latter situation holds for the action of pyrophosphate in the modification of reduced diphosphopyridine nucleotide’ to the product obtained by the action of 3-phosphogly...

The rate of hydrolysis of adenosine triphosphate and the binding of inorganic pyrophosphate to myosin vary inversely with increasing concentration of free Mg++, in the presence of a magnesium ethylenediaminetetraacetate buffer system; half-maximum binding of pyrophosphate and 50% inhibition of adenosine triphosphatase activity occur at a free Mg++ concentration about 10M7 M at 3O. The binding o...

A l*C-diterpene alcohol (copalol) was isolated as its 4-(4’nitrophenylazo)benzoyl ester from a soluble enzyme system which had been prepared from a cell-free extract of mycelia of the fungus Gibberella fujikuroi and incubated with ZJ*Cmevalonate, ATP, and MgC12. Copalol was identified as trans-( -)-labda-8(16), 13-dien-15-01 from its properties, in comparison with those of the enantiomeric alco...

Hydroxymethyl glutaryl (HMG)-coenzyme A (CoA) reductase inhibitors (statins) protect the myocardium against ischemia-reperfusion injury via a mechanism unrelated to cholesterol lowering. Statins may inhibit isoprenylation and thereby prevent activation of proteins such as RhoA. We hypothesized that statins protect the myocardium against ischemia-reperfusion injury via a mechanism involving inhi...

A procedure was devised to detect and assay uridine 5'-pyrophosphate (UDP)-glucuronic acid pyrophosphorylase in plant extracts. Substrates are UDP-glucuronic acid and (32)P-pyrophosphate, and the (32)P-uridine 5'-triphosphate produced is selectively adsorbed to charcoal. The charcoal adsorption procedure is a modification of that used to determine (32)P-adenosine 5'-triphosphate produced by ade...