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Biomedical subjects

R L Soffer

Publications and source records attributed to R L Soffer.

At least 37 records · Page 2Linked to original sources
PubMed1982

Molecular and catalytic properties of rabbit testicular dipeptidyl carboxypeptidase.

Rabbit testicular dipeptidyl carboxypeptidase activity was purified by a procedure exploiting its affinity for N-alpha-[1-(S)-carboxy-3-phenylpropyl]-L-lysyl-L-proline. The molecular, catalytic, and immunological properties of the testicular enzyme are presented and compared with the corresponding properties of pulmonary angiotensin-converting enzyme. Although catalytically similar and immunologically related to pulmonary dipeptidyl carboxypeptidase, the testicular enzyme has a molecular weight (100,000) which is lower by a factor of about one-third and differs in its NH2 and COOH termini. Furthermore, we present evidence that the testicular enzyme is not a post-translation product of the pulmonary type enzyme. These data suggest that testicular and pulmonary dipeptidyl carboxypeptidase are two distinct proteins which are catalytically similar and immunologically closely related.

Amino Acids↗
PubMed1982

Tissue-specific expression of mRNAs for dipeptidyl carboxypeptidase isoenzymes.

The molecular weight of newly synthesized dipeptidyl carboxypeptidase (angiotensin-converting enzyme; peptidyldipeptide hydrolase, EC 3.4.15.1) polypeptide primed in a reticulocyte lysate by poly(A)-containing RNA from mature rabbit testis was only about 65% that of the immunologically related species programmed by pulmonary RNA. Furthermore, in contrast to the pulmonary RNA-dependent product, the synthesis of this testicular protein was not directed by RNA from testes of immature animals. These findings indicate that a shorter polypeptide chain and pubertal expression--the structural and regulatory properties that distinguish the testicular dipeptidyl carboxypeptidase isozyme--are determined pretranslationally.

Animals↗
PubMed1978

Canine pulmonary angiotensin-converting enzyme. Physicochemical, catalytic and immunological properties.

Antiontensin-converting enzyme (peptidyldipeptide hydrolase, EC 3.4.15.1) has been solubilized from canine pulmonary particles and purified to apparent homogeneity. A value of approx. 140000 was estimated for the molecular weight of the native and the reduced, denatured forms of the enzyme. No free NH2-terminal residue was detected by the dansylation procedure. Carbohydrate accounted for 17% of the weight of the enzyme, and the major residues were galactose, mannose and N-acetylglucosamine with smaller amounts of sialic acid and fucose. Removal of sialic acid residues with neuraminidase did not alter enzymatic activity. The enzyme contained one molar equivalent of zinc. Addition of this metal reversed stimulation and inhibition of activity observed in the presence of Co2+ and Mn2+, respectively. Immunologic homology of pure dog and rabbit enzymes was demonstrable with goat antisera. Fab fragments and intact IgG antibodies displayed similar inhibition dose vs. response curves with homologous enzyme, whereas the fragments were poor inhibitors of heterologous activity compared to the holoantibodies. The canine glycoprotein was much less active than the rabbit preparation in catalyzing hydrolysis of Hip-His-Leu. In contrast, the two enzymes exhibited comparable kinetic parameters with angiotensin I as substrate.

Amino Acid Sequence↗
PubMed1978

Reversal of renovascular hypertension by antibodies specific for angiotensin-converting enzyme.

Goat antibodies developed against pure rabbit pulmonary angiotensin-converting enzyme (peptidyl dipeptidase, EC 3.4.15.1) were administered intravenously to rats with two-kidney Goldblatt hypertension and to normotensive animals. In the hypertensive model these antibodies were associated with a sustained, immune-dependent decrease of blood pressure to normal values. A smaller, but also immune-specific, reduction of blood pressure was observed in the normotensive group. The data suggest that heterologous antibody directed against angiotensin-converting enzyme may provide a biologically specific probe for examining the contribution of the renin-angiotensin system to normal and pathologic circulatory states.

Animals↗
PubMed1978

Escherichia coli mutants defective in dipeptidyl carboxypeptidase.

Two independent mutants of Escherichia coli deficient in dipeptidyl carboxypeptidase activity (Dep-) were isolated after mutagenesis with ethyl methanesulfonate. Mating experiments and introduction of specific episomes indicated that the responsible gene was located at approximately 27--31 min on the E. coli chromosome. The Dep- mutants differed from the parental strain in their inability to grow with N-acetylalanylalanylalanine as the sole nitrogen source. Revertants selected for growth on this substrate of the enzyme were found to have reacquired the activity. Enzyme activity was highly sensitive to inhibition by 1-(D-3-mercapto-2-methylpropanoyl)-L-proline (SQ 14225), a potent inhibitor of mammalian dipeptidyl carboxypeptidase (angiotensin-converting enzyme, peptidyl dipeptidase, EC 3.4.15.1). This compound also reduced the rate of growth of the wild type with N-acetylalanylalanylalanine but not with ammonium sulfate. A fraction of the enzyme was released into the medium by osmotic shock, indicating that its presence in the periplasmic space may account for growth with N-acetylated peptides that cannot be taken up by E. coli. In addition to providing information about the specific role of this exopeptidase in E. coli, the Dep- mutants may prove useful for delineating the regulation and cellular function of dipeptidyl carboxypeptidases in higher organisms.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1977

Pleiotropic phenotype of an Escherichia coli mutant lacking leucyl-, phenylalanyl-transfer ribonucleic acid-protein transferase.

A mutant of Escherichia coli that lacks leucyl-, phenylalanyl-transfer ribonucleic acid-protein transferase had diminished activities of L-phenylalanyl-transfer ribonucleic acid synthetase and tryptophanase, grew faster than its parent with aspartic acid as the sole nitrogen source, accumulated higher levels of enterochelin in the medium during iron limitation, and exhibited an abnormal morphology.

Acyltransferases↗
PubMed1976

Pulmonary angiotensin-converting enzyme antienzyme antibody.

A method has been developed for quantitating anticatalytic activity in antibody preparations made in goats against pure solubilized angiotensin-converting enzyme from rabbit pulmonary membranes. Anticatalytic activity was purified about 90-fold from a single batch of serum by a procedure including diethylaminoethylcellulose chromatography and elution from Sepharose columns containing covalently bound pure enzyme. Antiholoenzyme antibody was fractionated with respect to charge and binding affinity; however, these different populations each inhibited enzymatic hydrolysis of hippurylhistidylleucine, angiotensin I, and bradykinin. The inhibition dose-response curves were similar for hydrolysis of hippurylhistidylleucine and angiotensin I despite the difference in molecular weight of these substrates. Evidence is presented suggesting that a single molecule of antibody can bind two molecules of enzyme and that at least 18% of the total antiholoenzyme antibody population is directed against determinants which influence catalytic activity. A competitive immunoassay was developed with radioiodinated pulmonary enzyme as displaceable antigen. The anticatalytic and radioimmune assays were used to examine immunological properties of converting enzymes in various rabbit organs and fluids. Kidney, brain, and serum were found to contain converting enzymes which were immunologically identified with that in rabbit lung. Converting enzyme in seminal plasma was similar to the lung enzyme in the anticatalytic assay, but showed lower immunoreactivity in the radioimmune assay.

Animals↗
PubMed1976

Pulmonary angiotensin-converting enzyme. Interspecies homology and inhibition by heterologous antibody in vivo.

Goat antibody against pure rabbit pulmonary angiotensin-converting enzyme was used to probe homology of converting enzymes from other species. Immunologically cross-reactive material was found in detergent-solubilized extracts of lung particles from rat, guinea pig, and dog by double immunodiffusion, radioimmunoassay, and inhibition of enzyme activity. No homology was demonstrable with bovine, frog, or chicken lung extracts. Antibodies from different individual goats yielded comparable estimates of homology by immunodiffusion and radioimmunoassay. In contrast, they varied greatly in extent and specificity of their inhibitory action on heterologous enzyme activity. The vasopressor effect of angiotensin I and the vasodepressor effect of bradykinin were diminished and potentiated, respectively, in rats treated with anti-rabbit enzyme antibody. A smaller but significant immune-dependent inhibition of the vasopressor response to angiotensin II was also observed.

Angiotensin II↗
PubMed1976

Angiotensin-converting enzyme: vascular endothelial localization.

Fluorescein-labeled antibody to rabbit pulmonary angiotensin-converting enzyme localized in the vascular endothelium of rabbit lung, liver, adrenal cortex, pancreas, kidney, and spleen. Epithelial cells of the renal proximal tubules were the only parenchymal cells among the organs studied that demonstrated immunoreactivity.

Adrenal Cortex↗