This investigation was designed to determine whether a defect in energy utilization exists in heart failure. Accordingly, the direct conversion of chemical energy to mechanical work was studied in right ventricular papillary muscles from normal cats and cats with experimental right ventricular failure secondary to pulmonary artery constriction. Energy production was inhibited by iodoacetic acid...

The pH rate profile for the hydrolysis of diethyl-p-nitrophenyl phosphate catalyzed by the phosphotriesterase from Pseudomonas diminuta shows a requirement for the deprotonation of an ionizable group for full catalytic activity. This functional group has an apparent pKa of 6.1 +/- 0.1 at 25 degrees C, delta Hion of 7.9 kcal/mol, and delta Sion of -1.4 cal/K.mol. The enzyme is not inactivated in...

Proteolytic enzymes from plant tissues have in general resisted purification more successfully than those of animal origin. Proteinases have been extracted from many plants, among them yeast (9), pineapple (27), pumpkin (27), beans,’ and wheat (4), but much concentration and purification are usually required before a preparation of even moderate activity is obtained. This presents difficulties ...

Reduction and alkylation of human myeloperoxidase under nondenaturing conditions results in the cleavage of this enzyme. Sedimentation equilibrium data is presented which shows that the molecular weight of the cleavage product (78,000 +/- 2,000) is half that of the native enzyme (153,000 +/- 4,000). We conclude that the cleavage product is the half-enzyme hemi-myeloperoxidase. Hemi-myeloperoxid...

The enzymic conversion of proglobulin to globulin catalyzed by the extracts of vacuoles isolated from developing pumpkin (Cucurbita sp. cv Kurokawa Amakuri Nankin) cotyledons was investigated. The endoplasmic reticulum fraction isolated from the developing cotyledons pulselabeled with [(35)S]methionine was shown to contain mainly the radiolabeled proglobulin, which was used as a substrate for a...

The ptp gene of Acinetobacter johnsonii was previously reported to encode a low-molecular-mass protein, Ptp, whose amino acid sequence, predicted from the theoretical analysis of the nucleotide sequence of the gene, exhibits a high degree of similarity with those of different eukaryotic and prokaryotic phosphotyrosine-protein phophatases. We have now overexpressed the ptp gene in Escherichia co...

Excitatory stimulation in hippocampal slices results in biphasic NAD(P)H fluorescence transients. Previous studies using differing stimulus protocols agreed that the oxidation phase is a consequence of mitochondrial metabolism, but the reduction phase has been attributed to (1) mitochondrial nicotinamide adenine dinucleotide (NADH) generation or (2) astrocytic glycolysis triggered by glutamate ...

The region(s) of bovine galactosyltransferase that interacts with the lactose synthase regulatory protein a-lactalbumin was investigated using trace 3H acetylation to probe the effects of a-lactalbumin on the reactivities of the individual amino groups of galactosyltransferase. In the presence of Mn2+, a-lactalbumin was found to reduce the reactivities of lysines 93 and 181 and to increase the ...

1. Effects of chemical modifiers : p-chloromercuric benzoate (PCMB) ; N-ethylmaleimide (NEM) ; iodoacetic acid (IAA) ; 5,5-dithiobis-2-nitrobenzoate (DTNB) ; and dinitrofiuorobenzene (FDNB), and of metabolic inhibitors : NaCN; and 2,4-dinitrophenol (DNP) on taste responses in the chorda tympani of rats were studied. 2. PCMB, NEM, and IAA at optimum concentrations depressed the sucrose response ...

Rabbit alveolar macrophages which were treated at 0 degrees C with phenylarsine oxide and then incubated at 37 degrees C for 10 min exhibited a two- to threefold increase in surface receptor activity for macroglobulin.protease complexes, diferric transferrin, and mannose-terminal glycoproteins. Analysis of the concentration-dependence of ligand binding indicated that changes in ligand-binding a...