Biomedical subjects
Publications and source records attributed to J Kobayashi.
The peptide toxins having inhibitory effects on the contractile response of the mouse diaphragm to direct stimulation, geographutoxin I and II, have been isolated from Conus geographus, and their amino acid compositions have been determined.
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A 14-membered ring diterpenoid named cembrane, possessing Ca-antagonistic action on the isolated rabbit aorta, has been isolated from a soft coral of the genus Sarcophyton, and its structure established by X-ray and spectroscopic data.
1. Tessulatoxin, a powerful vasoactive protein from the marine snail Conus tessulatus, has been purified by affinity and electrofocusing chromatography. 2. The purified protein is almost homogeneous on slab gel electrophoresis. 3. The molecular weight of tessulatoxin is 26,000: the lethal dose for the fish Rhodeus ocellatus smithi is 1 microgram/g. 4. This toxic protein (10(-7) approximately 5 X 10(-7) g/ml) causes a marked contraction of the rabbit isolated aorta, which is inhibited by verapamil (10(-6) M).
Two metal dependent proteases were investigated in rabbit uterus using a synthetic substrate, 2,4-dinitrophenyl-Pro-Gln-Gly-Ile-Ala-Gly-Gin-D-Arg (Dnp-peptide). One was extracted by homogenization in 50 mM Tris-HCl/0.25% Triton X-100/100 mM CaCl2, pH 7.4, from rabbit uterus, and the other from the insoluble fraction by heating at 60 degrees C for 4 min in 50 mM Tris-HCl/100 mM CaCl2, pH 7.4. Both enzymes were partially purified by gel filtration, ion-exchange chromatography and chromatofocusing, and further characterized. The soluble enzyme was a metal dependent peptidase, and hydrolysed 4-phenylazobenzyloxycarbonyl-Pro-Leu-Gly-Pro-D-Arg as well as Dnp-peptide. Its molecular weight was about 7.0 X 10(4), and the cleavage sites for Dnp-peptide were Gln-Gly and possibly Gly-Ile in the ratio of 3:1. On the other hand, the enzyme extracted from the insoluble fraction was present as a latent form, and was found to be activated by 4-aminophenylmercuric acetate but not by trypsin. The activated enzyme hydrolysed gelatin, in addition to Dnp-peptide, indicating that the enzyme is a gelatinase. The molecular weight was about 7.4 X 10(4) for the active form, and the cleavage site for Dnp-peptide was only the Gly-Ile bond. The rabbit uterine metal dependent peptidase obtained here had negligible activity on gelatin, but once it had been cleaved by the above gelatinase, the presence of metal dependent peptidase accelerated the action of gelatinase. Thus, the actions of both enzymes on gelatin were found to be synergistic.
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A myotoxin purified from Conus magus venom elicited complete loss of contractile response of the mouse diaphragm to electrical stimulation followed by a gradual rise in the baseline, an increase in the contractile force of the guinea-pig left atria, a tonic contraction of the guniea-pig taenia caeci and powerful rhythmic contractions of the guinea-pig ileum and vas deferens. These excitatory effects of the toxin were blocked by treatment with tetrodotoxin, suggesting that these effects were due to an increase in Na+ permeability of the cell membrane.
Eburnetoxin, a powerful vasoactive protein has been isolated from the venom of the marine snail Conus eburneus, monitored by the contractile effect to the rabbit aorta. The molecular weight was estimated to be 28,000 by gel permeation chromatography and slab gel electrophoresis. The purified protein was electrophoretically homogeneous. The toxin at concentrations above 3 X 10(-7) g/ml elicited a marked contractile response of aorta, which was inhibited by verapamil (10(-6) M). The minimum lethal dose in the fish Rhodeus ocellatus smithi was 1 microgram/g body weight.
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