Reevaluating the assay for rat steroid 5 alpha-reductase isozymes in prostate and epididymis homogenates we encountered an extreme pH-dependency of the type II isozyme. The time-course of the metabolism of testosterone (T) to 17 beta-hydroxy-5 alpha-androstan-3-one (DHT) at acidic pH shows an initial burst when the homogenate is not brought to pH before the start of the incubation. Therefore, t...

Isozyme patterns of 23 different enzymes were compared in normal, benign, and malignant breast tissues; in MCF-7 cells; and in organoids of normal human breast tissue. Benign lesions generally showed isozyme patterns similar to those of normal tissues. Lactate dehydrogenase isozyme 5 was significantly increased in malignant tumors; MCF-7 cells had only lactate dehydrogenase (L-lactate:NAD oxido...

Isozyme Profiles and Specific Organ Damage. CORNISH, HERBERT H., BARTH, MARY L., and DODSON, VERNON N. (1970). Toxicol. Appl. Pharmacol 16,41 l-423. Serum lactic dehydrogenase isozymes have been utilized as a means of detecting specific organ damage in rats. The serum LDH isozyme patterns seen in response to liver or kidney damage are markedly different, thus these patterns were utiiized to ide...

Calmodulin(CaM)-dependent cyclic nucleotide phosphodiesterase (PDE1) plays a critical role in the complex interactions between the cyclic nucleotide and Ca(2+) second messenger systems. Bovine brain contains two major PDE1 isozymes, designated according to tissue origin and subunit molecular mass as brain 60 kDa and 63 kDa PDE1 isozymes. Kinetic properties suggest that 63 kDa PDE1 isozyme is di...

A striking correlation between neural expression and high net negative charge in some teleost isozymes led to the interesting, yet untested, suggestion that negative charge represents an adaptation (via natural selection) to the neural environment. We examine the evolution of the triosephosphate isomerase (TPI) gene family in fishes for periods of positive selection. Teleost fish express two TP...

In a recent study on Gulf War veterans who developed delayed neurotoxicity symptoms, we found their levels of serum paraoxonase (PON1) isozyme type Q to be significantly lower than in the control, unaffected veteran group. These results were obtained in 25 ill veterans and 20 well control subjects, of which 10 were deployed and 10 were nondeployed battalion members who remained in the United St...

As part of a study of the regulation of aspartate aminotransferase isozymes (EC 2.6.1. l), we have investigated the characteristics of inhibition of the anionic and cationic isozymes by u-erythrose 4-phosphate and glycolaldehyde phosphate, the naturally occurring homologues of D-glyceraldehyde 3-phosphate. Erythrose-4-P has been found to be a time-dependent inhibitor of both the cationic and an...

From the Departments of Medicine and Pathology, University of California Los Angeles School of Medicine, Los Angeles, California 90024, and the Veterans Administration Center, Los Angeles, California 90073; the Departments of Pediatrics and Internal Medicine, University of Rochester School of Medicine and Strong Memorial Hospital, Rochester, New York 14620; and the Department of Medicine, Dartm...

In all eukaryotic cells that have been examined, specific membrane arrays are induced in response to increased levels of the ER membrane protein, HMG-CoA reductase. Analysis of these inducible membranes has the potential to reveal basic insights into general membrane assembly. Yeast express two HMG-CoA reductase isozymes, and each isozyme induces a morphologically distinct proliferation of the ...

Crude extracts of triple-cloned, purified cultures of 22 species of Mycoplasma and Acholeplasma were examined for expression of 21 isozyme systems routinely used to type mammalian cells. Nine previously described enzymes (purine nucleoside phosphorylase, adenylate kinase, dipeptidase, esterase, glyceraldehyde-3-phosphate dehydrogenase, glucose phosphate isomerase, glucose-6-phosphate dehydrogen...