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Photoproduction of hydrogen by membranes of green photosynthetic bacteria

Description: Photoproduction of H/sub 2/ from ascorbate by unit-membrane vesicles from Chlorobium limicola f. thiosulfatophilum was achieved with a system containing gramicidin D, tetramethyl-p-phenylenediamine, methyl viologen, dithioerythritol, Clostridium hydrogenase, and an oxygen-scavenging mixture of glucose, glucose oxidase, ethanol, and catalase. Maximum quantum yield was less than one percent. Half maximum rate of H/sub 2/ production occurred at a white-light intensity of approximately 0.15 cm/sup … more
Date: January 1, 1980
Creator: Bernstein, J D & Olson, J M
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Does oxygen enhance the radiation-induced inactivation of penicillinase. Progress report, December 1, 1979-November 30, 1980

Description: The radiation-induced inactivation of penicillinase in dilute aqueous solutions buffered with phosphate was studied, by examining enzyme radiosensitivity in the presence of various gases (He, O/sub 2/, H/sub 2/, N/sub 2/O, N/sub 2/O + O/sub 2/). The introduction of either N/sub 2/O or O/sub 2/ was found to reduce the radiodamage. On the other hand H/sub 2/ or N/sub 2/O + O/sub 2/ gas-mixture enhanced the radiosensitivity. In the presence of formate and oxygen, no enzyme inactivation was detecte… more
Date: January 1, 1980
Creator: Samuni, A.; Kalkstein, A. & Czapski, G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Autoxidation and cytotoxicity

Description: A comprehensive synthesis, or reaction schema, to relate autoxidations of non-lipid compounds to lipid chain peroxidation in vivo is presented. This is done in the context of cytotoxic autoxidation reactions, and it is concluded that hydroxyl radicals produced by iron-dependent Fenton reactions serve as both primary toxicants and as sources of secondary toxicants. The latter stem from lipid chain peroxidation initiated by the Fenton-derived hydroxyl radicals, which are visualized as the obligat… more
Date: January 1, 1980
Creator: Borg, D C; Schaich, K M & Elmore, Jr, J J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comprehensive progress report, 1977-1980

Description: Research accomplishments and activities during the past three year period are described. Specific projects were: (1) restriction endonuclease studies of tetrahymena mtDNA; (2) biosynthesis of mitochondrial tRNA; and (3) structure and synthesis of tRNA charging enzymes. (ACR)
Date: January 1, 1980
Creator: Suyama, Y
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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DNA replication and the repair of DNA strand breaks in nuclei of Physarum polycephalum. Terminal report, August 1, 1978-March 31, 1980

Description: Nuclei isolated from Physarum are able to replicate approximately 15% of the total genome in a manner which is qualitatively similar to the DNA replication process occurring in the intact organism. Such nuclei, however, are defective in the joining of Okazaki intermediates in vitro. Two DNA polymerase species, isolated from nuclei or intact plasmodia of this organism, can be separated by sucrose density gradient centrifugation. Total DNA polymerase activity is low in nuclei isolated during mito… more
Date: January 1, 1980
Creator: Brewer, E. N. & Evans, T. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Nature of oxygen containing radicals in radiation chemistry and photochemistry of aqueous solutions. Annual progress report, September 1979-July 1980

Description: During this year, emphasis will be given on the properties of HO/sub 2/ and O/sub 2//sup -/ and OH, mainly in their role in biological systems. We will continue to study and elucidate how O/sub 2//sup -/ reacts in biological systems. The toxicity of O/sub 2//sup -/ is quite well established but the mechanism is still obscure. One way O/sub 2//sup -/ is toxic is that OH is formed from O/sub 2//sup -/ through reduction of Fe/sup 3 +/, and subsequently the reaction of Fe/sup 2 +/ with H/sub 2/O/su… more
Date: January 1, 1980
Creator: Czapski, G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Role of. pi. -cation radicals in the enzymatic cycles of peroxidases, catalases, and nitrite and sulfite reductases

Description: Charge iterative extended Hueckel calculations, and magnetic and optical results on porphyrins, chlorins, and isobacteriochlorins (1) suggest that the catalytic cycles of the enzymes horseradish peroxidase, catalase, Neurospora crassa catalase, and nitrite and sulfite reductases proceed via ..pi..-cation radicals of their prosthetic groups; (2) offer distinguishing features for the optical and magnetic spectra of these radicals, pertinent to their detection as enzymatic intermediates; (3) recon… more
Date: January 1, 1980
Creator: Hanson, L K; Chang, C K; Davis, M S & Fajer, J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Purification and Studies of Mammalian Glyoxalase Enzymes

Description: The glyoxalase system, which has been known since 1913, is widely distributed in nature. The system consists of two enzymes, glyoxalase I and glyoxalase II. Methylglyoxal is very unstable and undergoes oxidation and polymerization reactions. One of the purposes of this study was to find a simple, convenient and reproducible method of methylglyoxal preparation. Another objective was the purification of both glyoxalase enzymes employing affinity chromatography as a major step. The purified enzyme… more
Date: December 1980
Creator: Oray, Bedii
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Repair of DNA treated with. gamma. -irradiation and chemical carcinogens. Progress report, March 15, 1979-March 15, 1980

Description: The identification and purification of 3-methyladenine glycosylase from the cell nuclei of rat liver was completed. The characterization of 7-methylguanine N-glycosylase activity in E. coli is currently under investigation. Alkylated DNA in chromatin structures as a substrate for 3-methyladenine N-glycosylase is discussed. An enzyme from E. coli and mammalian tissue active on 2,6-diamino-4-hydroxy-5-N-methyldormamido-pyrimide is isolated and characterized. Studies are proceeding on the correlat… more
Date: January 1, 1980
Creator: Goldthwait, D.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Structural relationship in chloroplast membranes. Final report, August 1, 1977-August 31, 1980

Description: Methodology has been developed for the isolation and characterization of pigment-proteins from chloroplast membranes. Characterization of these pigment-proteins has increased our understanding of mechanisms regulating the efficiency of photosynthetic light harvesting during photosynthesis. Incorporation of isolated pigment-protein complexes into model membranes has allowed simulation of grana stacks; these structural features of chloroplasts play a key role in maintaining appropriate interactio… more
Date: September 1980
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Photoreactivation in bacteria and in skin

Description: In many procaryotic and eucaryotic cells, photoreactivating enzyme mediates light-dependent repair of uv-induced damage; the enzyme binds to a pyrimidine dimer in DNA, and, on absorption of a photon (300 to 600 nm), specifically monomerizes the dimer, thus repairing the DNA. Photoreactivating enzyme has been found in human tissues and human cells in culture can photoreactivate cellular dimers, and can mediate photoreactivation of Herpes (human fibroblasts) and Epstein-Barr virus (human leukocyt… more
Date: January 1, 1980
Creator: Sutherland, B. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Pollen genetic markers for detection of mutagens in the environment

Description: To utilize and exploit pollen for in situ mutagen monitoring, screening and toxicology, the range of genetic traits in pollen must be identified and analyzed. To be useful for the development of mutagen detection systems proteins should be: (1) activity stainable or immunologically identifiable in the pollen, (2) the products of one to three loci; and (3) gametophytic and nuclear in origin. Several proteins, including alcohol dehydrogenase in maize, which meet these criteria are discussed. The … more
Date: January 1, 1980
Creator: Nilan, R.A.; Rosichan, J.L.; Arenaz, P.; Hodgdon, A.L. & Kleinhofs, A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Inducible error-prone repair in B. subtilis. Progress report, September 1, 1979-February 28, 1981

Description: The mechanism of activation and the mode of action of the SOS system in Bacillus subtilis are being investigated. Interesting aspects of the SOS system in B. subtilis include: (1) the differences between the SOS functions in this bacterium and in the enteric bacteria; (2) the spontaneous activation of SOS functions in competent cells; and (3) the difficulty in establishing the presence of error-prone repair in this bacterium. In order to characterize the SOS system of B. subtilis, attempts will… more
Date: October 1, 1980
Creator: Yasbin, R E
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Utilization of agricultural wastes for production of ethanol. Progress report, October 1979-May 1980

Description: The project proposes to develop methods to utilize agricultural wastes, especially cottonseed hulls and peanut shells to produce ethanol. Initial steps will involve development of methods to break down cellulose to a usable form of substrates for chemical or biological digestion. The process of ethanol production will consist of (a) preparatory step to separate fibrous (cellulose) and non-fibrous (non-cellulosic compounds). The non-cellulosic residues which may include grains, fats or other sub… more
Date: May 1, 1980
Creator: Singh, B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

PROTEOLYTIC REMOVAL OF THE CARBOXYL TERMINUS OF THE T4 GENE 32 HELIX-DESTABILIZING PROTEIN ALTERS THE T4 IN VITRO REPLICATION COMPLEX

Description: The proteolytic removal of about 60 amino acids from the COOH terminus of the bacteriophage T4 helix-destabilizing protein (gene 32 protein) produces 32*I, a 27,000-dalton fragment which still binds tightly and cooperatively to single-stranded DNA. The substitution of 32*I protein for intact 32 protein in the seven-protein T4 replication complex results in dramatic changes in some of the reactions catalyzed by this in vitro DNA replication system, while leaving others largely unperturbed. (1) L… more
Date: July 1, 1980
Creator: Burke, R.L.; Alberts, B.M. & Hosoda, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Biotechnological research and development for biomass conversion to chemicals and fuels

Description: It is likely that a growing need to produce chemicals and fuels from renewable resources will stimulate the development of biotechnology as a commerical enterprise of considerable potential. The purpose of the analysis and the development structure that could lead to establishing this new technology are presented. Two general goals are recommended: (i) in the near term, to revive the older fermentation industry and, by the addition of sophisticated technology, to make it competitive; (ii) in th… more
Date: August 1980
Creator: Villet, Ruxton
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Metabolism of fatty acids in rat brain in microsomal membranes

Description: Using a technique in which substrate fatty acids are incorporated into microsomal membranes followd by comparison of their rates of desaturation or elongation with those of exogenous added fatty acids it has been found that the desaturation rate is more rapid for the membrane-bound substrate than for the added fatty acid. Moreover, the product of the membrane-bound substrate is incorporated into membrane phospholipid whereas the product of the exogenous substrate is found in di- and triacyl gly… more
Date: January 1, 1980
Creator: Aeberhard, Ernesto E.; Gan-Elepano, Minerva & Mead, James F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

(Accumulation of Methyl-Deficient Rat Liver Messenger Ribonucleic Acid on Ethionine Administration). Progress Report. [Methyltransferase Activity in Ehrlich Ascites Tumor Cells and Effects of Phorbol Ester on Methyltransferase Activity]

Description: Enzyme fractions were isolated from Ehrlich ascites cells which introduced methyl groups into methyl deficient rat liver mRNA and unmethylated vaccinia mRNA. The methyl groups were incorporated at the 5'; end into cap 1 structures by the viral enzyme, whereas both cap 0 and cap 1 structures were formed by the Ehrlich ascites cell enzymes. Preliminary results indicate the presence of adenine N/sup 6/-methyltransferase activity in Ehrlich ascites cells. These results indicate that mRNA deficient … more
Date: January 1, 1980
Creator: Borek, E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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