Amino acid sequences of the alpha and beta chains of adult hemoglobin of the slender loris, Loris tardigradus. (9/6919)

alpha and beta chains from adult hemoglobin of the slender loris (Loris tardigradus) were isolated by Amberlite CG-50 column chromatography. After S-aminoethylation, both chains were digested with trypsin and the amino acid sequences of the tryptic peptides obtained were analyzed. Further, the order of these tryptic peptides in each chain was deduced from their homology with the primary structures of alpha and beta chains of human adult hemoglobin. Comparing the primary structures of the alpha and beta chains of adult hemoglobin of the slender loris thus obtained with those of adult hemoglobin of the slow loris, 4 amino acid substitutions in the alpha chains and 2 in the beta chains were recognized.  (+info)

A new antibiotic XK-90. II. The structure of XK-90. (10/6919)

The new antibiotic, XK-90, produced by Streptomyces sp. is active against Gram-positive and Gram-negative bacteria. The structure has been determined as N-acetyl-N'-(3-formyl-4-hydroxyphenyl)hydrazine (1) and is the second example of a naturally occurring antibiotic having the phenylhydrazine skeleton.  (+info)

Comparative study of carbohydrate-protein complexes. II. Determination of hydroxylysine and its glycosides in human skin and scar collagens by an improved method. (11/6919)

A modification of the existing methods for measuring hydroxylysine, galactosylhydroxylysine, and glucosylgalactosylhydroxylysine is described. The method is based on analysis with an automated amino acid analyzer using a conventional separation system for basic amino acids. The prior removal of acidic and neutral amino acids was necessary. This was achieved by passing an alkaline hydrolysate of collagen through a column of Amberlite CG-120, Type II (H+) and washing the column with 8% aqueous pyridine. A basic fraction containing the hydroxylysine compounds was then recovered from the column by elution with 3 M NH4OH. Model experiments showed that hydroxylysine and its glycosides could be analyzed with an hour and that recoveries exceeded 90%. This method was applied to human tissues to investigate whether the dermal scar is different in collagen composition from normal skin. With the limited number of samples analyzed, the data suggested that long-standing scar tissues reverted to a composition similar to that of normal skin. The composition of hydroxylysine-linked carbohydrate units is also discussed on the basis of the age-related change.  (+info)

beta-lactam antibiotics. II. Structure-activity relationships of 6-[alpha-(alpha'-ureido-acylamino) acylamino] penicillanic acids. (12/6919)

The influence on the structure-activity relationships (S.A.R.) of the stereochemistry and various alkyl, aryl, aralkyl and heterocyclic substituents at the two chiral centres in the dipeptide side-chain of a new series of penicillins was examined. In many cases the effects of these changes had a pronounced influence on the degree of activity against Gram-positive and especially Gram-negative bacteria. Several compounds indicated that the size, shape and spatial disposition of a substituent were the parameters of importance in influencing activity, rather than it lipophilic or electronic character. The most active homologues in the series provided broad-spectrum penicillins which in terms of their in vitro antibacterial properties showed improvements over certain of the marketed penicillins. Thus 6-[D-alpha(alpha'-ureidoacyl-amino)acylamino]penicillanic acids were found which had a carbenicillin-like profile, with improvements against Pseudomonas aeruginosa, Klebsiella aerogenes, sensitive and beta-lactamase-producing Gram-positive cocci.  (+info)

New antibiotics, enaminomycins A, B and C. II. Physico-chemical and biological properties. (13/6919)

Physico-chemical characterization of enaminomycins revealed that these antibiotics are new members of the epoxy quinone family. From elementary analysis and mass spectroscopic measurements the molecular formulae of enaminomycins A, B and C appear to be C7H5NO5, C10H11N06 and C7H7NO5, respectively. They are very unique in their chemical properties, possessing various functions, such as epoxy, primary amine and carboxylic acid, in their small structural units. Enaminomycin A, the most potent component, has activity against Gram-positive and Gram-negative bacteria and shows cytostatic effect on L1210 mouse leukemia cells in vitro, but enaminomycins B and C are only weakly active against Gram-positive and Gram-negative bacteria.  (+info)

Isolation of ekatetrone, a new metabolite of producing variants of Streptomyces aureofaciens. (14/6919)

From a mixture of substances formed by producing strains of Streptomyces aureofaciens under conditions of submerged fermentation a new metabolite, ekatetrone, was isolated. Its isolation and basic physical and chemical data are described. Ekatetrone is a quinone derivative with a carboxamide group. In tests in vitro with cells of Ehrlich's ascites tumour evidence was provided that ekatetrone inhibits proteo- and nucleosynthesis.  (+info)

The structure of ekatetrone, a metabolite of strains of Streptomyces aureofaciens. (15/6919)

The structure of ekatetrone has been determined from physico-chemical data obtained using the natural compound, its derivatives and products of degradation reactions. Ekatetrone was found to be the lactone of 1,8-dihydroxy-2-(1'-hydroxy-2'-carbamoyl)ethyl-9,10-anthraquinone-3-acetic acid (I). It is proposed that ekatetrone is related, biogenetically, to protetrone.  (+info)

Paraquat toxicity: proposed mechanism of action involving lipid peroxidation. (16/6919)

The purpose of this study was to investigate the hypothesis that paraquat pulmonary toxicity results from cyclic reduction-oxidation of paraquat with sequential generation of superoxide radicals and singlet oxygen and initiation of lipid peroxidation. In vitro mouse lung microsomes catalyzed an NADPH-dependent, single-electron reduction of paraquat. Incubation of paraquat with NADPH, NADPH-cytochrome c reductase, and purified microsomal lipid increased malondialdehyde production is a concentration dependent manner. Addition of either superoxide dismutase or a single oxygen trapping agent 1,3-dipheylisobenzo furan inhibited paraquat stimulated lipid peroxidation. In vivo, pretreatment of mice with phenobarbital decreased paraquat toxicity, possibly by competing for electrons which might otherwise reduce paraquat. In contrast, paraquat toxicity in mice was increased by exposure to 100% oxygen and by deficiencies of the antioxidants selenium, vitamin E, or reduced glutahione (GSH). Paraquat, given IP to mice, at 30 mg/kg, decreased concentrations of the water-soluble antioxidant GSH in liver and lipid soluble antioxidants in lung. Oxygen-tolerant rats, which hae increased activities of pulmonary enzymes which combat lipid peroxidation, were also tolerant to lethal doses of paraquat as indicated by an increased paraquat LT50. Furthermore, rats chronically exposed to 100 ppm paraquat in the water had elevated pulmonary activities of glucose-6-phosphate dehydrogenase and GSH reductase. These results were consistent with the hypothesis that lipid peroxidation is involved in the toxicity of paraquat.  (+info)