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Biomedical subjects

R Kobayashi

Publications and source records attributed to R Kobayashi.

At least 433 records · Page 24Linked to original sources
PubMed1981

The specificity of porcine pancreatic protease E.

A procedure for the preparation of porcine protease E is described. The availability of a convenient source of the enzyme has permitted specificity studies utilizing the macromolecular substrates oxidized insulin A and B chains and oxidized ribonuclease. The results show that protease E has a pronounced selectivity for the carbonyl bonds of serine threonine, alanine, and valine residues, with the latter most favored. The specificity is complementary to that of the chymotrypsins and we suggest that this property is physiologically significant. The k3 and Km values for the substrates acetyl-trialanine methyl ester, succinyltrialanine p-nitroanilide and benzoylalanine methyl ester are comparable to those observed by others for porcine elastase. The specificity observed in the present work, however, indicates that protease E may best be regarded as a member of the chymotrypsin group of enzymes.

Amino Acid Sequence↗
PubMed1981

Identification of zymogen E in a complex with bovine procarboxypeptidase A.

The presence of zymogen E in bovine pancreatic secretion was demonstrated by activation with trypsin and isolation of protease E. The enzyme, pI = 4.85, has k3 and Km values of 48 s-1 and 4.4 mM, respectively, for acetyl-tri-L-alanine methyl ester and an amino acid composition similar to that of porcine protease E. Gel filtration of the proteins in the secretion provided evidence that bovine zymogen E forms complexes with procarboxypeptidase A, including a ternary complex of these two proteins with chymotrypsinogen C. Taken together with previous observations on porcine zymogen E (Kobayashi, R., Kobayashi, Y., and Hirs, C. H. W. (1978) J. Biol. Chem. 253, 5526-5530) the data suggest that complex formation between procarboxypeptidase A and zymogen E may be a more widespread property of these proteins. The fact that zymogen E occurs as a major constituent in bovine pancreatic secretion in a physiological context n which no requirement for elastolysis exists suggests further that the functional significance of protease E in the digestion of proteins is general and not specific for elastin.

Amino Acids↗
PubMed1981

Syntheses of 9-substituted josamycin, 13-substituted isojosamycin and their tetrahydro derivatives.

Derivatives of josamycin and isojosamycin modified at C-9 and C-13 have been prepared by reaction sequences involving treatment of josamycin with alcohols, phenol or 1-methyl-1H-tetrazol-5-ylthiol in acidic media. Several tetrahydro derivatives of josamycin and isojosamycin have also been prepared by reaction sequences involving catalytic hydrogenation. From the 1H NMR studies, it was found that the conformation of the macro-lactone portion of 13-O-methylisojosamycin dimethylacetal, a key intermediate, is flexible and changeable with variation of the solvent.

Anti-Bacterial Agents↗
PubMed1979

Concurrent hypersecretion of aldosterone and cortisol from the adrenal cortical adenoma.

Hypertension, hypokalemia, suppressed plasma renin activity and increased plasma aldosterone were found in a middle-aged woman. Following removal of the tumor in the left adrenal gland these abnormalities disappeared. Concurrently, however, the plasma cortisol level did not show normal diurnal change, although the value at 6 A.M. was within the normal range. Administration of 2 mg dexamethasone failed to depress the plasma cortisol level and urinary 17-OHCS concentrations. Postoperatively, plasma cortisol and urinary 17-OHCS were below normal. Histologic examination of the tumor indicated the presence of two types of adenoma cells; one was a large watery clear cell with rich lipid and possibly with aldosterone secretion and the other was an acidophilic cell with poor lipid and possibly with cortisol secretion. It is suggested that, in addition to oversecretion of aldosterone, the tumor autonomously secreted cortisol, although the amount of cortisol secreted was not large enough to produce typical Cushing's syndrome.

Adenoma↗
PubMed1979

Purification and characterization of a troponin C-like phosphodiesterase activator from bovine thyroid.

A troponin C-like phosphodiesterase activator from bovine thyroid has been purified to homogeneity. The overall purification was about 9,800-fold with a yield of 8%. Bovine thyroid activator protein is identical in biologic properties to that isolated from bovine brain. They have the same specific activity regarding stimulation of bovine brain cyclic nucleotide phosphodiesterase. Both proteins form a Ca2+-dependent complex with heart muscle troponin I which is stable in 6M urea-polyacrylamide gel and which is similar, but not identical, to the troponin C-troponin I complex. The physiochemical properties of bovine thyroid activator protein are identical with those of bovine brain and other phosphodiesterase activator proteins and are similar to heart muscle and skeletal muscle troponin C as follows: (A) they bind 3-4 exchangeable calcium ions/mol with dissociation constants between 10(-5) and 10(-6) M, (B) they are highly acidic with a high content of aspartic and glutamic acids and isoelectric points of approximately 4.1, (C) these proteins have an unusual ultraviolet absorption spectrum with six discrete maxima between 250 and 284 nm which are characteristic of phenylalanine and tyrosine, and (D) these proteins have a low content of cysteine, histidine, tyrosine and proline. The tryptic peptide maps of bovine thyroid and brain activator protein are very similar. However, despite a very similar amino acid composition, the peptide map of bovine heart muscle troponin C is significantly different from that of the other two proteins. The molecular weight of thyroid and brain activator protein is 16,500, while that of heart troponin C is 18,500. Thyroid and brain activator protein, as well as heart troponin C, appear to undergo significant Ca2+-dependent conformational changes, as measured by the difference in the circular dichroism spectrum and electrophoretic mobility observed in the presence and absence of calcium ion.

Amino Acids↗
PubMed1978

Chromosomal location of genes participating in the degradation of purines in Pseudomonas aeruginosa.

Genetic mapping of the genes (puu) that encode the enzymes catalysing degradation of purines in Pseudomonas aeruginosa strain PAO has been carried out. Mutants that are deficient in adenine deaminase (puuA), guanine deaminase (puuB), xanthine dehydrogenase (puuC), uricase (puuD), allantoinase (puuE), and/or allantoicase (puuF) were isolated and used for the genetic study. Conjugation by FP5 factor and generalized transduction by phage G101 gave the following map locations of these six genes on the chromosome: hisI--puuB--hisII; trpA,B--puuA--ilv202; met9011--catA1--tyu--nar9011--(puuC, puuD, puuE)--puuF. A close linkage among the puuC, puuD and puuE was demonstrated by the transduction.

Acetates↗
PubMed1978

Identification of a binary complex of procarboxypeptidase A and a precursor of protease E in porcine pancreatic secretion.

In porcine pancreatic secretion procarboxypeptidase A exists in two states: as a monomer and as a binary complex of a type hitherto not observed in the pancreatic secretions of other species. This complex is shown to contain 1 molecule of procarboxypeptidase A and 1 molecule of a proteolytic zymogen we have designated as zymogen E. The two subunits of the complex have been separated by gel filtration in a denaturing solvent and the products used for compositional and NH2-terminal sequence analysis. We also fractionated the mixture obtained on activation of the binary complex and isolated homogenous preparations of porcine carboxypeptidase A and the diisopropylphosphoryl derivative of the enzyme formed from zymogen E. Zymogen E has an Mr of about 26,000 and on activation produces an enzyme of essentially the same Mr with properties very similar to those of human pancreatic protease E. It catalyzes the esterolysis of acetyl-L-alanyl-L-analyl-L-alanine methyl ester, but is inert towards acetyl-L-tyrosine ethyl ester and is readily inactivated by diisopropylophosphorofluoridate. Zymogen E has an amino acid composition different from those of porcine chymotrypsinogen A, B, or C. Its NH2-terminal sequence shows homology with the NH2-terminal sequence of lungfish proelastase A; yet, like human protease E, porcine protease E has relatively very low activity on intact elastin.

Amino Acid Sequence↗
PubMed1978

An increase of pituitary 3', 5' cyclic adenosine monophosphate produced by estradiol benzoate in vitro: possible implication of this increase in the secretion of luteinizing hormone.

In an attempt to study the site and mechanism of action of estrogen in producing positive feedback control, porcine anterior pituitary slices were incubated in vitro in the presence of estradiol benzoate (EB). EB elevated pituitary cyclic AMP concentration within 5 min and augmented pituitary release of luteinizing hormone (LH). The magnitude of increase of cyclic AMP and LH release was related to the doses of EB used. Also, luteinizing hormone releasing hormone (LH-RH) elevated pituitary cyclic AMP concentration and stimulated pituitary release of LH. The magnitude of increase of cyclic AMP and LH release was inversely related to the doses of LH-RH used. EB and LH-RH were additive in increasing cyclic AMP. Progesterone and clomiphene citrate interfered with an increase of pituitary cyclic AMP produced by EB, but did not significantly affect the basal level of pituitary cyclic AMP. Testosterone propionate, human chorionic gonadotropin and hexestrol were without effect on either basal or stimulated level of pituitary cyclic AMP. Since cyclic AMP and dibutyryl cyclic AMP (DBC) stimulated LH release, it is suggested that EB directly stimulates the release of LH by augmenting cyclic AMP synthesis in the anterior pituitary.

Animals↗
PubMed1978

Partial gonadotrophin-resistance in pseudohypoparathyroidism.

A patient with classical Albright's pseudohypoparathyroidism was investigated because of oligomenorrhoea. Hypo-oestrogenism was associated with elevated basal gonadotrophin values [mean basal serum LH and FSH were 272 +/- 84 (SD) ng/ml and 593 +/- 83 ng/ml, resplectively (normal less than or equal to 220 and less than or equal to 400, respectively)]. The response to gonadotrophin releasing hormone (Gn-RH) was exaggerated, with maximal LH and FSH increments of 1688 and 458 ng/ml, respectively. These results and the findings on ovarian biopsy were compatible with partial ovarian resistance to gonadotrophins. This resistance could be overcome by administration of human menopausal gonadotrophins. This is the first evidence for gonadotrophin resistance in pseudohypoparathyroidism. The plasma cyclic adenosine-3',5'-monophosphate response to glucagon administration by two different protocols was about 70% that of normal control subjects. Other endocrine glands whose responses to hormones are mediated via the adenylate cyclase system evidenced minor abnormalities of questionable significance. This indirect evidence is compatible with a more extensive defect in the adenylate cyclase system in pseudohypoparathyroidism than has hitherto been suspected.

Adenylyl Cyclases↗