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  Partner: UNT Libraries
 Degree Discipline: Biochemistry
A Quantitative Radioimmunoassay for Phosphoglucose Isomerase and Its Utilization in Detecting Cross-Reactive Material in Variant Forms of Phosphoglucose Isomerase and in Human Tissues

A Quantitative Radioimmunoassay for Phosphoglucose Isomerase and Its Utilization in Detecting Cross-Reactive Material in Variant Forms of Phosphoglucose Isomerase and in Human Tissues

Date: May 1979
Creator: Purdy, Kimberly L.
Description: A method for purification and radiolabelling phosphoglucose isomerase was devised in order to develop a sensitive quantitative radioimmunoassay for the detection of the enzyme irrespective of its catalytic activity. For four genetic variants of PGI no difference in the molecular specific activity was observed. In one variant (PGI-Denton), liver and heart tissue extracts, and in mature erythrocytes (as compared to normal erythrocytes), a decreased molecular specific activity was observed which initially may imply that these samples contain cross-reactive material which is not catalytically active.
Contributing Partner: UNT Libraries
NAD+-Dependent 15-Hydroxyprostaglandin Dehydrogenase from Swine Kidney: Characterization and Kinetic Mechanism

NAD+-Dependent 15-Hydroxyprostaglandin Dehydrogenase from Swine Kidney: Characterization and Kinetic Mechanism

Date: December 1979
Creator: Kung-Chao, Diana T.-Y.
Description: Cytoplasmic 15-hydroxyprostaglandin dehydrogenase from swine kidney was purified to specific activity of 1.2 U per mg protein, by chromatographic techniques. Native molecular weight of enzyme was estimated at 45,000. Enzyme was inhibited by sulfhydryls, diuretics, and various fatty acids. Substrate studies indicated NAD+ specificity and ability to catabolize prostaglandins, except prostaglandin B and thromboxane B. Initial velocity studies gave intersecting plots conforming to a sequential mechanism. 15-keto-prostaglandin exhibited linear noncompetitive production inhibition with respect to either prostaglandin or NAD+; NAD yielded linear competitive production inhibition with respect to NADH. Results, and those of dead-end inhibition and alternated substrate studies, are consistent with an ordered Bi-Bi mechanism: NAD+ is added first, then prostaglandin; then 15-keto-rostaglandin is released, then NADH.
Contributing Partner: UNT Libraries
Analysis of Human Transfer RNA Gene Heteroclusters

Analysis of Human Transfer RNA Gene Heteroclusters

Date: December 1986
Creator: Chang, Yung-Nien
Description: Two phage lambda clones encompassing human tRNA genes have been isolated from a human gene library harbored in bacteriophage lambda Charon-UA. One of the clones (designated as hLeuU) containing a 20-kb human DNA fragment was isolated and found to contain a cluster of four tRNA genes. An 8.2-kb Hindlll fragment encompassing the four tRNA genes was isolated from the 20-kb fragment and subcloned into pBR322 for restriction mapping and DNA sequence analysis. The four tRNA genes are arranged as two tandem pairs with the first pair containing a proline tRNAAGQ gene and a leucine tRNAAAQ gene and the second pair containing another proline tRNAAGG gene and a threonine tRNAuQU gene. The two pairs are separated about 3 kb from each other, and the leucine tRNAAAG gene is of opposite polarity from the other three tRNA genes. The tRNA transcription units were sequenced by a unidirectional deletion dideoxyribonucleotide chain-termination method in the M13mpl8 and 19 vectors. The coding regions of the four tRNA genes contain characteristic internal split promoter sequences and do not encode intervening sequences nor the CCA trinucleotide found in mature tRNAs. The proline t R N A A G G gene is separated from the leucine t R ...
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Purification, Characterization and Receptor Binding of Human Colony-Stimulating Factor-1

Purification, Characterization and Receptor Binding of Human Colony-Stimulating Factor-1

Date: May 1987
Creator: Shieh, Jae-Hung
Description: Human colony-stimulating factor-1 (CSF-1) was purified from the serum-free conditioned medium of a human pancreatic carcinoma cell line. The four-step procedure included chromatography on DEAE Sepharose, Con A Sepharose and HPLC on phenyl column and reverse-phase C-3 column. The purity of human CSF-1 was demonstrated by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS—PAGE) as a single diffuse band with a molecular weight (Mr) of 42,000-50,000 and was further confirmed by a single amino-terminal amino acid residue of glutamate. Under reducing conditions, purified CSF-1 appeared on SDS-PAGE as a single protein band with a Mr of 21,000-25,000 and concurrently lost its biological activity, indicating that human CSF-1 consists of two similar subunits and that the intact quaternary structure is essential for biological activity. When treated with neuraminidase and endo-8~D~N—acetylglucosaminidase D, the Mr of CSF-1 was reduced to 36,000-40,000 and to a Mr of 18,000-20,000 in the presence of mercaptoethanol.
Contributing Partner: UNT Libraries
Studies on Hog Plasma Lecithin:cholesterol Acyltransferase: Isolation and Characterization of the Enzyme

Studies on Hog Plasma Lecithin:cholesterol Acyltransferase: Isolation and Characterization of the Enzyme

Date: May 1987
Creator: Park, Yong Bok
Description: Lecithin:cholesterol acyltransferase (LCAT) was isolated from hog plasma and basic physicochemical properties and functionally important regions were investigated. Approximately one milligram of the enzyme was purified to apparent homogeneity with approximately a 20,000-fold increase in specific activity. In the plasma, hog LCAT was found to associate with high-density lipoproteins (HDL) probably through hydrophobic interactions with apolipoprotein A-I. HDL was the preferred lipoprotein substrate of the enzyme as its macromolecular substrate. The enzyme was found to contain 4 free sulfhydryl groups; at least one of these appeared to be essential for catalytic activity. The enzyme had a tendency to aggregate at high concentrations. More than half of the tryptophan and none of the tyrosine residues of the enzyme were shown to be exposed to the aqueous environment based on fluorescence and absorbance studies, respectively.
Contributing Partner: UNT Libraries
Physical, Chemical and Catalytic Properties of the Isozymes of Bovine Glucose Phosphate Isomerase

Physical, Chemical and Catalytic Properties of the Isozymes of Bovine Glucose Phosphate Isomerase

Date: August 1987
Creator: Cini, John Kenneth
Description: Glucose phosphate isomerase (GPI) occurs in different bovine tissues as multiple, catalytically active isozymes which can be resolved by polyacrylamide gel electrophoresis and isoelectric focusing. GPI from bovine heart was purified to homogeneity and each of the isozymes was resolved. Four of the five isozymes were characterized with regard to their physical, chemical and catalytic properties in order to establish their possible physiological significance and to ascertain their molecular basis. The isozymes exhibited identical native (118 Kd) and subunit (59 Kd) molecular weights but had different apparent pi values of 7.2, 7.0, 6.8 and 6.6. Structural analyses showed that the amino terminus was blocked and the carboxyl terminal sequence was -Glu-Ala-Ser-Gly for all four isozymes. The most basic isozyme was more stable than the more acidic isozymes (lower pi values) at pH extremes, at high ionic strength, in the presence of denaturants or upon exposure to proteases. Kinetic constants, such as turnover number, Km and Ki values, were identical for all isozymes. Identical amino acid composition and peptide mapping by chemical cleavage at methionine and cysteine residues of the isozymes suggest a postsynthetic modification rather then a genetic origin for the in vivo isozymes. When the most basic isozyme was ...
Contributing Partner: UNT Libraries
Studies of Enzyme Mechanism Using Isotopic Probes

Studies of Enzyme Mechanism Using Isotopic Probes

Date: August 1987
Creator: Chen, Cheau-Yun
Description: The isotope partitioning studies of the Ascaris suum NAD-malic enzyme reaction were examined with five transitory complexes including E:NAD, E:NAD:Mg, E:malate, E:Mg:malate, and E:NAD:malate. Three productive complexes, E:NAD, E:NAD:Mg, and E:Mg:malate, were obtained, suggesting a steady-state random mechanism. Data for trapping with E:14C-NAD indicate a rapid equilibrium addition of Mg2+ prior to the addition of malate. Trapping with 14C-malate could only be obtained from the E:Mg2+:14C-malate complex, while no trapping from E:14C-malate was obtained under feasible experimental conditions. Most likely, E:malate is non-productive, as has been suggested from the kinetic analysis. The experiment with E:NAD:malate could not be carried out due to the turnover of trace amounts of malate dehydrogenase in the pulse solution. The equations for the isotope partitioning studies varying two substrates in the chase solution in an ordered terreactant reaction were derived, allowing a determination of the relative rates of substrate dissociation to the catalytic reaction for each of the productive transitory complexes. NAD and malate are released from the central complex at an identical rate, equal to the catalytic rate.
Contributing Partner: UNT Libraries
Mechanism of the Adenosine 3',5'-Monophosphate Dependent Protein Kinase

Mechanism of the Adenosine 3',5'-Monophosphate Dependent Protein Kinase

Date: May 1988
Creator: Kong, Cheng-Te
Description: Isotope partitioning experiments were carried out with the adenosine 3',5'-monophosphate-dependent protein kinase catalytic subunit (cAPK) from bovine hearts to obtain information on the order of addition of reactants and the relative rates of reactant release from enzyme compared to the catalytic step(s). A value of 100% trapping for both ErMgATP-[γ-32P] and E:3H-Serpeptide at low Mgf indicates that MgATP and Serpeptide dissociate slowly from the enzyme compared to the catalytic step(s). The K_Serpeptide for MgATP trapping is 17 μM, while the K_MgATP for Serpeptide trapping is 0.58 mM. The latter data indicate that the off-rate for MgATP from the E:MgATP complex is 14 s^-1 while that for Serpeptide from the E: Serpeptide complex is 64 s^-1. At high Mg^, 100% trapping is obtained for the E:MgATP-[γ-32P] complex but only 40% is obtained for the E:Serpeptide complex. Thus, the off-rate for Serpeptide from the E:MgATP:Serpeptide complex becomes significant at high Mg_f. Data suggest a random mechanism in which MgATP is sticky. The V for the cAPK reaction increases 1.5-1.7 fold in the presence of the R_II in the presence of saturating cAMP at a stoichiometry of R:C of 1:1. No change is obtained with the type-I complex under these conditions. At higher ...
Contributing Partner: UNT Libraries
Alternate Substrates and Isotope Effects as a Probe of the Malic Enzyme Reaction

Alternate Substrates and Isotope Effects as a Probe of the Malic Enzyme Reaction

Date: August 1988
Creator: Gavva, Sandhya Reddy
Description: Dissociation constants for alternate dirmcleotide substrates and competitive inhibitors suggest that the dinucleotide binding site of the Ascaris suum NAD-malic enzyme is hydrophobic in the vicinity of the nicotinamide ring. Changes in the divalent metal ion activator from Mg^2+ to Mn^2+ or Cd^2+ results in a decrease in the dinucleotide affinity and an increase in the affinity for malate. Primary deuterium and 13-C isotope effects obtained with the different metal ions suggest either a change in the transition state structure for the hydride transfer or decarboxylation steps or both. Deuterium isotope effects are finite whether reactants are maintained at saturating or limiting concentrations with all the metal ions and dinucleotide substrates used. With Cd^2+ as the divalent metal ion, inactivation of the enzyme occurs whether enzyme alone is present or is turning over. Upon inactivation only Cd^2+ ions are bound to the enzyme which becomes denatured. Modification of the enzyme to give an SCN-enzyme decreases the ability of Cd^2+ to cause inactivation. The modified enzyme generally exhibits increases in K_NAD and K_i_metai and decreases in V_max as the metal size increases from Mg^2+ to Mn^2+ or Cd^2+, indicative of crowding in the site. In all cases, affinity for malate greatly ...
Contributing Partner: UNT Libraries
Kinetic and Chemical Mechanism of Pyrophosphate-Dependent Phosphofructokinase

Kinetic and Chemical Mechanism of Pyrophosphate-Dependent Phosphofructokinase

Date: December 1988
Creator: Cho, Yong Kweon
Description: Data obtained from isotope exchange at equilibrium, exchange of inorganic phosphate against forward reaction flux, and positional isotope exchange of 18O from the (βγ-bridge position of pyrophosphate to a (β-nonbridge position all indicate that the pyrophosphate-dependent phosphofructokinase from Propionibacterium freudenreichii has a rapid equilibrium random kinetic mechanism. All exchange reactions are strongly inhibited at high concentrations of the fructose 6-phosphate/Pi and MgPPi/Pi substrate-product pairs and weakly inhibited at high concentrations of the MgPPi/fructose 1,6-bisphosphate pair suggesting three dead-end complexes, E:F6P:Pi, E:MgPPi:Pi, and E:FBP:MgPPi. Neither back-exchange by [32p] nor positional isotope exchange of 18O-bridge-labeled pyrophosphate was observed under any conditions, suggesting that either the chemical interconversion step or a step prior to it limits the overall rate of the reaction. Reduction of the pyridoxal 5'-phosphate-inactivated enzyme with NaB[3H]4 indicates that about 7 lysines are modified in free enzyme and fructose 1,6-bisphosphate protects 2 of these from modification. The pH dependence of the enzyme-reactant dissociation constants suggests that the phosphates of fructose 6-phosphate, fructose 1,6-bisphosphate, inorganic phosphate, and Mg-pyrophosphate must be completely ionized and that lysines are present in the vicinity of the 1- and 6-phosphates of the sugar phosphate and bisphosphates probably directly coordinated to these phosphates. The pH dependence of ...
Contributing Partner: UNT Libraries
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