Biomedical subjects
Publications and source records attributed to A L Chandra.
A soil streptomycete (Streptomyces sp. A11) degraded collagen isolated from bovine Achilles tendon, calf skin, human placenta, carp swim bladder and rat tail tendon and released appreciable quantities of hydroxyproline. It also degraded hide powder and vegetable tanned leather. The organism was taxonomically characterized, compared with allied species, identified and designated as Streptomyces wartii.
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Streptomyces species 3M grew in peptone yeast extract medium with 1000 micrograms/ml K2Cr2O7. Incubation of the chromate with different cell fractions in the presence of NADH and NADPH resulted in a decrease of Cr6+ in the reaction mixture. The level of Cr6+ was reduced by 82.7% by a particulate cell fraction obtained by centrifugation at 105,000 x g for 1 h, in the presence of NADH. The reducing enzyme was associated with this cell fraction. The enzyme was constitutive and reduced Cr6+ to Cr3+.
Keratinase produced from Streptomyces Sp.A11 decomposed human hair, chicken feather, wool, silk and pure keratin extracted from human epidermis. Purification of the enzyme by DEAE-cellulose column chromatography resulted in 7.5-fold increase in activity relative to the activity of the culture filtrate. The enzyme was inducible, extracellular, homogeneous with a molecular weight of 49,000. The enzyme activity was inhibited by reduced glutathione, phenylmethyl sulphonyl fluoride and 2-mercaptoethanol.
A soil streptomycete designated as Streptomyces sp. A8 produced an extracellular collagen hydrolysing enzyme that appeared to be 'true collagenase' as it degraded native collagen under physiological conditions and cleaved the synthetic hexapeptide 4-phenylazobenzyloxycarbonyl-L-prolyl-L-leucyl-glycyl-L-prolyl-D-a rginine into two tripeptides. The enzyme was purified by diethyl aminoethyl cellulose chromatography and Sephadex G-150 gel filtration. The purified enzyme had an apparent molecular weight of about 75,000 by SDS-polyacrylamide gel electrophoresis. Treatment with lithium chloride did not dissociate it into subunits. A strong inhibition was observed with chelating agents such as alpha-alpha-dipyridyl and 8-hydroxyquinoline. Ethylene diamine tetraacetate completely inhibited the enzyme activity. Among the cations tested only Ca2+ and Mg2+ enhanced the collagenase activity. Heavy metal ions like Pb2+, Ag+, Cu2+ and Zn2+ strongly inhibited the enzyme. The EDTA inhibition could be reversed with Ca2+. Cysteine and reduced glutathione caused significant reduction in enzyme activity. Parachloromercuribenzoate and iodoacetamide had no effect on the collagenase. Amino acid analysis revealed the absence of cysteine and tyrosine. Many of the properties were the same as collagenases of Clostridium histolyticum and Vibrio alginolyticus.
A soil streptomycete hydrolysed collagen extracted from bovine Achilles tendon, calf skin, carp swim bladder and rat tail tendon. Enzyme activity was highest with rat tail tendon collagen as substrate. The taxonomy of the streptomycete was studied according to internationally approved methods. Comparative studies revealed that it resembled Streptomyces humidus , S. rochei and S. distatochromogenes in some respects, but differed in many cultural and physiological characteristics. Based on these differences the organism was given a new identity as Streptomyces species A.
Acmycin, a new polyene antibiotic, was fungistatic at low and fungicidal at high concentrations. It produced malformations in conidia of Helminthosporium oryzae and Curvularia lunata and caused leakage of yeast cells. Acmycin was fairly nontoxic to germinating seeds. The intravenous LD50 was 300-400 and intraperitoneal maximum tolerated dose 100-500 mg/kg body mass of mice.
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A new antifungal antibiotic named acmycin was isolated from a soil streptomycete. Detailed comparative taxonomic studies showed that the organism differed from three related species of streptomycetes. The organism was referred to as Streptomyces sp. AC2. The isolated antibiotic appears to be of polyene nature.
A soil streptomycete degraded hair, silk, wool, feather and leather which were collected from solid wastes. The organism was identified taxonomically and designated Streptomyces sp. A956. It degraded leather to the maximum extent and solubilized 35.9% of the total nitrogen, 2.32 mg of glycine equivalent amino nitrogen could be obtained by degradation of 100 mg leather.
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An antibiotic designated A28 was isolated from a soil streptomycete which showed wide antibacterial activity. The antibiotic was extracted and purified into a yellow powder. Its physico-chemical and antimicrobial properties indicated that it is a novel peptide antibiotic.
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