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C E Odya

Publications and source records attributed to C E Odya.

24 records · Page 2Linked to original sources
PubMed1978

Purification and properties of prolylcarboxypeptidase (angiotensinase C) from human kidney.

Prolylcarboxypeptidase was purified from human kidney 1200-fold with 18% yield. The enzyme had no cathepsin A activity and appeared to be homogeneous in gel electrophoresis. The molecular weight of prolylcarboxypeptidase was estimated to be 115,000 by gel filtration. Under denaturing conditions the enzyme dissociated into subunits of 45,000 and 66,500 molecular weight. The enzyme cleaved benzyloxycarbonyl (Cbz)-Pro-Phe, representing the COOH-terminal end of angiotensin II and des-Asp1-angiotensin II (angiotensin III), at a rate of 31 micronmol/h/mg of protein. The rate of hydrolysis increased when phenylalanine in the N-protected dipeptide was replaced with alanine, valine, or leucine or when the octapeptide angiotensin II or the heptapeptide angiotensin III were the substrates. The enzyme also cleaved the angiotensin II antagonist saralasin (Sar1-Ala8-angiotensin II). The Km values were 1 mM, 2mM, and 0.77 mM with Cbz-Pro-Phe, angiotensin II, and angiotensin III, respectively. The enzyme had an acid pH optimum (4.5 to 5.5), but hydrolyzed angiotensin III at pH 7 at 50% of the optimal rate. Prolylcarboxypeptidase was inhibited by diisopropyl phosphorofluoridate and pepstatin, but not by sequestering agents or -SH reagents.

Angiotensin II↗
PubMed1978

Aspects of bradykinin radioimmunoassay.

125I-derivatives of Tyr1-kallidin, Tyr5-bradykinin, and Tyr8-bradykinin were prepared. A technique for purification of the monoiodinated derivative is described. Bradykinin antisera were tested for their ability to bind the mono-iodinated analogues. Each antiserum had a characteristic preference for one of the three labeled peptides. The sensitivity of each antiserum was greatest when it was used with the label bound most avidly by that antiserum. The specificity of an antiserum was not changed by varying the labeled analogue. Some common enzyme inhibitors had significant effects on the antigen-antibody reactions. Lecithin interfered with the reaction between antiserum and Tyr1-kallidin. The data suggest that antisera for bradykinin radioimmunoassay be tested with several radioactive iodobradykinins to maximize their usefulness. In addition, enzyme inhibitors used to stabilize levels of kinins in biological fluids should be tested for their effects on the assay. Biologic samples rich in lipid may give spurious radioimmunoassay results unless they are freed of those phospholipids that can bind labeled and unlabeled peptides.

Animals↗
PubMed1978

Gestational changes in pulmonary converting enzyme activity in the fetal rabbit.

Changes in angiotensin-converting enzyme were measured in the lungs of fetal rabbits isolated and perfused in situ at varying ages from 22 days gestation to 7 days of age under controlled conditions of flow, pH, and temperature. Enzyme activity was assessed by infusing bradykinin or angiotensin I in Krebs-Henseleit solution and measuring residual peptide in the effluent by radioimmunoassay. The levels of substrate studied were below those required for enzyme saturation. Lungs of 22 day gestation fetuses removed only one-third of either peptide. The activity at term and in neonatal life resulted in more than 80% peptide removal. The time of the greatest rise in the percent substrate cleared occurs earlier than the time of the greatest increase in lung and body weight. The lower percentage of substrate cleared in early gestation appears to result in part from a limited surface area for enzyme activity in the primitive fetal pulmonary microvascular bed, since morphological studies with fluorescein-tagged anticonverting enzyme antibody demonstrated the presence of enzyme in the lung as early as 17 days of gestation. Electron micrographs of the pulmonary endothelial cell surface reveal that the degree of surface infolding and hence surface area increases with gestation. The higher percentage of substrate cleared in later gestation closely parallels the structural and ultrastructural development of the vascular bed. The presence of converting enzyme in the placenta by the second third of gestation and the large size of the placenta suggest that this organ may be a major locus of converting enzyme activity in the fetus.

Angiotensin I↗