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Evidence for a role of the multifunctional calcium/calmodulin-dependent protein kinase II in insulin secretion

Description: Calcium/calmodulin-dependent protein kinase II (CaM kinase II) is demonstrated to exist in the ß-cell and immunopecipitation. Glucose and potassium significantly stimulate the rapid autophosphorylation of CaM kinase II and proportionally induce autonomous activity of the kinase in a dose-dependent manner that parallels insulin secretion. The activation of CaM kinase II, alloxan, KN-62 and KN-93, suggest that the enzyme is an integral component of insulin secretion and/or related processes in the β-cell.
Date: December 1993
Creator: Wenham, Robert M. (Robert Michael)
Partner: UNT Libraries

A proposed molecular mechanism for the activation of a calcium/phospholipid-dependent protein kinase in P1798 lymphosarcoma

Description: Calcium/phospholipid-dependent protein kinase (PKC) was purified from P1798 lymphosarcoma. It was demonstrated that uncomplexed calcium and uncomplexed phosphatidylserine are the activators, that the activation of PKC requires that calcium bind first, that the activation of PKC requires that calcium bind first, that high calcium concentrations inhibit PKC activation, and that calcium inhibition can be overcome by phosphatidylserine.
Date: May 1987
Creator: Elson, James L.
Partner: UNT Libraries

Studies on the structure and function of glucosephosphate isomerases: chemical modifications, chemical cleavages and structural analyses

Description: Human glucosephosphate isomerase was subjected to a series of chemical modifications aimed at identifying residues essential for catalytic activity. Specific lysyl, arginyl, tryptophanyl and histidyl residues were found to react stoichiometrically with pyridoxal-5'-phosphate-NaBH4, 2,3-butadione, N-bromosuccinimide and N-bromoacetylethanolamine phosphate, respectively.
Date: December 1981
Creator: Lu, Hsieng Sen
Partner: UNT Libraries

Ultramicro Methods in Biochemistry: [Part] 1. General Consideration, [Part] 2. Procedures for the Determination of Serum Bilirubin

Description: From Introduction: "The purpose of this paper is first to present a positive, but initial, approach that has been taken to meet these requirements, and second to report in detail the ultramicro method developed and evaluated for determining serum bilirubin. Subsequent publications will set forth the techniques finalized for other biochemical constituents."
Date: October 1962
Creator: Van Stewart, E.; Puckett, Charles R. & Wood, Agnes
Partner: UNT Libraries Government Documents Department

Purification and Studies of Methylglyoxal Reductase from Sheep Liver

Description: The objectives of these investigations were (1) the purification of MG reductase from sheep liver and (2) studies of some of its characteristics. MG reductase was purified 40 fold and showed a single band on SDS-PAGE. Molecular weight estimations with SDS-PAGE showed a molecular weight of 44,000; although gel filtration with Sephadex G-150 gave a molecular weight of 87,000 indicating that the enzyme might be a dimer. The Km for MG is 1.42 mM and for NADH it is 0.04 mM. The pH optimum for the purified enzyme is pH 7.0. Isoelectric focusing experiments showed a pI of 9.3. In vivo experiments involving rats treated with 3,3',5-triiodothyronine (T_3) and 6-n-propyl-2-thiouracil (PTU) indicated that MG reductase was depressed by T_3 and elevated by PTU.
Date: May 1983
Creator: Lambert, Patricia A.
Partner: UNT Libraries

High resolution fractionation, characterization, and studies of ADP-ribose polymers

Description: A method for the high resolution fractionation of ADP-ribose polymers has been developed that allows isolation of highly purified polymers of defined size and branching fequency. The key features of the method are purification using dihydroxyboronyl-BioRex 70 and fractionation by anion exchange HPLC.
Date: August 1992
Creator: Kiehlbauch, Charles C. (Charles Coffey)
Partner: UNT Libraries

Purification and characterization of a differentiation factor from rat lung conditioned medium

Description: A Differentiation Factor (DF) was purified from rat lung conditioned medium by a four-steps procedure. The DF has a molecular weight of 27000, and an isoelectric point of 4.70. Although DF is stable up to 60°C, it is sensitive to digestion by trypsin, chymotrypsin and subtilisin. DF forms granulocyte colonies in soft agar. Studies using anti-NRK CSF antibody demonstrated that DF is distinct from GM-CSF.
Date: May 1988
Creator: Ansari, Naser A. (Naser Awni)
Partner: UNT Libraries

Complex polymers of ADP-ribose occur in vitro and in vivo

Description: The work presented here included the development of a highly sensitive method to estimate the size and complexity of poly(ADP-ribose). This involved radiolabeling of the precursor pools, purification of polymers using a boronate resin, polymer fractionation according to size by molecular sieve chromatography and analysis of polymer complexity by enzymatic digestion to nucleotides which were quantified by strong anion exchange chromatography.
Date: May 1985
Creator: Alvarez-Gonzalez, Rafael
Partner: UNT Libraries

Analysis of Biological Materials Using a Nuclear Microprobe

Description: The use of nuclear microprobe techniques including: Particle induced x-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) for elemental analysis and quantitative elemental imaging of biological samples is especially useful in biological and biomedical research because of its high sensitivity for physiologically important trace elements or toxic heavy metals. The nuclear microprobe of the Ion Beam Modification and Analysis Laboratory (IBMAL) has been used to study the enhancement in metal uptake of two different plants. The roots of corn (Zea mays) have been analyzed to study the enhancement of iron uptake by adding Fe (II) or Fe (III) of different concentrations to the germinating medium of the seeds. The Fe uptake enhancement effect produced by lacing the germinating medium with carbon nanotubes has also been investigated. The aim of this investigation is to ensure not only high crop yield but also Fe-rich food products especially from calcareous soil which covers 30% of world’s agricultural land. The result will help reduce iron deficiency anemia, which has been identified as the leading nutritional disorder especially in developing countries by the World Health Organization. For the second plant, Mexican marigold (Tagetes erecta), the effect of an arbuscular mycorrhizal fungi (Glomus intraradices) for the improvement of lead-phytoremediation of lead contaminated soil has been investigated. Phytoremediation provides an environmentally safe technique of removing toxic heavy metals (like lead), which can find their way into human food, from lands contaminated by human activities like mining or by natural disasters like earthquakes. The roots of Mexican marigold have been analyzed to study the role of arbuscular mycorrhizal fungi in enhancement of lead uptake from the contaminated rhizosphere.
Date: December 2014
Creator: Mulware, Stephen Juma
Partner: UNT Libraries

N-Acylethanolamines and Plant Phospholipase D

Description: Recently, three distinct isoforms of phospholipase D (PLD) were identified in Arabidopsis thaliana. PLD α represents the well-known form found in plants, while PLD β and γ have been only recently discovered (Pappan et al., 1997b; Qin et al., 1997). These isoforms differ in substrate selectivity and cofactors required for activity. Here, I report that PLD β and γ isoforms were active toward N-acylphosphatidylethanolamine (NAPE), but PLD α was not. The ability of PLD β and γ to hydrolyze NAPE marks a key difference from PLD α. N-acylethanolamines (NAE), the hydrolytic products of NAPE by PLD β and γ, inhibited PLD α from castor bean and cabbage. Inhibition of PLD α by NAE was dose-dependent and inversely proportional to acyl chain length and degree of unsaturation. Enzyme kinetic analysis suggested non-competitive inhibition of PLD α by NAE 14:0. In addition, a 1.2-kb tobacco (Nicotiana tabacum L.) cDNA fragment was isolated that possessed a 74% amino acid identity to Arabidopsis PLD β indicating that this isoform is expressed in tobacco cells. Collectively, these results provide evidence for NAE producing PLD activities and suggest a possible regulatory role for NAE with respect to PLD α.
Date: December 1998
Creator: Brown, Shea Austin
Partner: UNT Libraries

Kinetic and Chemical Mechanism of O-Acetylserine Sulfhydrylase-B from Salmonella Typhimurium

Description: Initial velocity studies of O-acetylserine sulfhydrylase-B (OASS-B) from Salmonella typhimurium using both natural and alternative substrates suggest a Bi Bi ping pong kinetic mechanism with double substrate competitive inhibition. The ping pong mechanism is corroborated by a qualitative and quantitative analysis of product and dead-end inhibition. Product inhibition by acetate is S-parabolic noncompetitive, indication of a combination of acetate with E followed by OAS. These data suggest some randomness to the OASS-B kinetic mechanism. The pH dependence of kinetic parameters was determined in order to obtain information on the acid-base chemical mechanism for the OASS-B reaction. A mechanism is proposed in which an enzyme general base accepts a proton from α-amine of O-acetylserine, while a second enzyme general base acts by polarizing the acetyl carbonyl assisting in the β-elimination of the acetyl group of O-acetylserine. The ε-amine of the active site lysine acts as a general base to abstract the α-proton in the β-elimination of acetate. At the end of the first half reaction the ε-amine of the active site lysine that formed the internal Schiff base and the general base are protonated. The resulting α-aminoacrylate intermediate undergoes a Michael addition with HS‾ and the active site lysine donates its proton to the α-carbon to give cysteine and regenerate enzyme to start the second half reaction. In addition, substrate specificity, stereochemistry of the internal Schiff base at C4', and sequence around active site lysine of O-acetylserine sulfhydrylase-A have been determined. The [4'-^3H]pyridoxamine generated by reduction of the internal Schiff base with sodium [^3H]borohydride retained most of its tritium after incubation with apoaspartate aminotransferase. These results agree with the hypothesis put forth by Dunathan (Dunathan, 1971; Dunathan and Voet, 1974) that a single surface (Re face) of the active site PLP is accessible to solvent. The sequence around the active site ...
Date: August 1993
Creator: Tai, Chia-Hui
Partner: UNT Libraries

2007 Plant Metabolic Engineering Gordon Conference and Graduate Research Seminar

Description: Plant Metabolic Engineering is an emerging field that integrates a diverse range of disciplines including plant genetics, genomics, biochemistry, chemistry and cell biology. The Gordon-Kenan Graduate Research Seminar (GRS) in Plant Metabolic Engineering was initiated to provide a unique opportunity for future researcher leaders to present their work in this field. It also creates an environment allowing for peer-review and critical assessment of work without the intimidation usually associated with the presence of senior investigators. The GRS immediately precedes the Plant Metabolic Engineering Gordon Research Conference and will be for and by graduate students and post-docs, with the assistance of the organizers listed.
Date: September 15, 2008
Creator: Grotewold, Erich
Partner: UNT Libraries Government Documents Department