UNT Theses and Dissertations - 51 Matching Results

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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 … more
Date: August 1993
Creator: Tai, Chia-Hui
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Autophosphorylation and Autoactivation of an S6/H4 Kinase Isolated From Human Placenta

Description: A number of protein kinases have been shown to undergo autophosphorylation, but few have demonstrated a coordinate increase or decrease in enzymatic activity as a result. Described here is a novel S6 kinase isolated from human placenta which autoactivates through autophosphorylation in vitro. This S6/H4 kinase, purified in an inactive state, was shown to be a protein of Mr of 60,000 as estimated by SDS-PAGE and could catalyze the phosphorylation of the synthetic peptide S6-21, the histone H4, a… more
Date: May 1994
Creator: Dennis, Patrick B. (Patrick Brian)
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Partner: UNT Libraries
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Plastidial carbonic anhydrase in cotton (Gossypium hirsutum L.): characterization, expression, and role in lipid biosynthesis

Description: Recently, plastidial carbonic anhydrase (CA, EC 4.2.1.1) cDNA clones encoding functional CA enzymes were isolated from a nonphotosynthetic cotton tissue. The role of CA in photosynthetic tissues have been well characterized, however there is almost no information for the role of CA in nonphotosynthetic tissues. A survey of relative CA transcript abundance and enzyme activity in different cotton organs revealed that there was substantial CA expression in cotyledons of seedlings and embryos, both… more
Date: August 2001
Creator: Hoang, Chau V.
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Partner: UNT Libraries
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Palmitoyl-acyl Carrier Protein Thioesterase in Cotton (Gossypium hirsutum L.): Biochemical and Molecular Characterization of a Major Mechanism for the Regulation of Palmitic Acid Content

Description: The relatively high level of palmitic acid (22 mol%) in cottonseeds may be due in part to the activity of a palmitoyl-acyl carrier protein (ACP) thioesterase (PATE). In embryo extracts, PATE activity was highest at the maximum rate of reserve accumulation (oil and protein). The cotton FatB mRNA transcript abundance also peaked during this developmental stage, paralleling the profiles of PATE enzyme activity and seed oil accumulation. A cotton FatB cDNA clone was isolated by screening a cDNA lib… more
Date: August 2001
Creator: Huynh, Tu T
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Physical, Chemical and Catalytic Properties of the Isozymes of Bovine Glucose Phosphate Isomerase

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… more
Date: August 1987
Creator: Cini, John Kenneth
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Functional Characterization of Plant Fatty Acid Amide Hydrolases

Description: Fatty acid amide hydrolase (FAAH) terminates the endocannabinoid signaling pathway that regulates numerous neurobehavioral processes in animals by hydrolyzing a class of lipid mediators, N-acylethanolamines (NAEs). Recent identification of an Arabidopsis FAAH homologue (AtFAAH) and several studies, especially those using AtFAAH overexpressing and knock-out lines suggest that a FAAH-mediated pathway exists in plants for the metabolism of endogenous NAEs. Here, I provide evidence to support this … more
Date: December 2010
Creator: Kim, Sang-Chul
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Studies of Enzyme Mechanism Using Isotopic Probes

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… more
Date: August 1987
Creator: Chen, Cheau-Yun
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Purification, Characterization and Receptor Binding of Human Colony-Stimulating Factor-1

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 … more
Date: May 1987
Creator: Shieh, Jae-Hung
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Partner: UNT Libraries
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Studies of the Mechanism of the Catalytic Subunit of cAMP Dependent Protein Kinase

Description: The kinetic mechanism of the cAMP-dependent protein kinase has been determined to be random in the direction of MgADP phosphorylation by using initial velocity studies in the absence and presence of the product, phospho-Serpeptide (Leu-Arg-Arg-Ala-Ser[P]-Leu-Gly) , and dead-end inhibitors. In contrast to the kinetic parameters obtained in the direction of Serpeptide phosphorylation, the only kinetic parameters affected by Mg^2+ are the dissociation constants for E:phospho-Serpeptide and E:MgADP… more
Date: August 1989
Creator: Yoon, Moon-Young
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Partner: UNT Libraries
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Kinetic and Chemical Mechanism of Pyrophosphate-Dependent Phosphofructokinase

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 subst… more
Date: December 1988
Creator: Cho, Yong Kweon
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Partner: UNT Libraries
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Studies on Hog Plasma Lecithin:cholesterol Acyltransferase: Isolation and Characterization of the Enzyme

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 substra… more
Date: May 1987
Creator: Park, Yong Bok
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Analysis of a Human Transfer RNA Gene Cluster and Characterization of the Transcription Unit and Two Processed Pseudogenes of Chimpanzee Triosephosphate Isomerase

Description: An 18.5-kb human DNA segment was selected from a human XCharon-4A library by hybridization to mammalian valine tRNAiAc and found to encompass a cluster of three tRNA genes. Two valine tRNA genes with anticodons of AAC and CAC, encoding the major and minor cytoplasmic valine tRNA isoacceptors, respectively, and a lysine tRNAcuu gene were identified by Southern blot hybridization and DNA sequence analysis of a 7.1-kb region of the human DNA insert. At least nine Alu family members were found inte… more
Date: August 1990
Creator: Craig, Leonard C. (Leonard Callaway)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Studies of the Mechanism of Plasma Cholesterol Esterification in Aged Rats

Description: The study was performed to determine factors influencing the esteriflcation of plasma cholesterol in young and aged rats. The distribution of LCAT activity was determined following gel nitration chromatography and ultracentrifugation of whole plasma respectively. When rat plasma was fractionated on a Bio-Gel A-5 Mcolumn, LCAT activity was found to be associated with the HDL fraction. A similar result was observed upon 24 hr density gradient ultracentrifugation of the plasma. However, following … more
Date: December 1989
Creator: Lee, Sun Min
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Alternate Substrates and Isotope Effects as a Probe of the Malic Enzyme Reaction

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 … more
Date: August 1988
Creator: Gavva, Sandhya Reddy
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Partner: UNT Libraries
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Mechanism of the Adenosine 3',5'-Monophosphate Dependent Protein Kinase

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… more
Date: May 1988
Creator: Kong, Cheng-Te
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Partner: UNT Libraries
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Purification of HMG-CoA Reductase and Regulation by Protein-Lipid Interactions

Description: The enzyme 3-Hydroxy-3- Methylglutaryl Coenzyme A Reductase catalyzes the rate limiting step of hepatic cholesterol biosynthesis and is unique among the enzymes in the early part of the pathway in that it is membrane bound. This gives rise to potential regulation of the enzyme through interactions with the endoplasmic reticulum membrane. A purification procedure has been developed which consistently produces enzyme of high specific activity. In order to fully characterize the interactions betwe… more
Date: December 1982
Creator: Brent, Lynn G. (Lynn Gran)
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Partner: UNT Libraries
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Modification of Cardiac Membrane Gsα by an Endogenous Arginine-Specific Mono-Adp-Ribosyltransferase

Description: The mechanism by which nicotinamide adenine dinucleotide (NAD) stimulates the activity of adenylate cyclase (AC) in canine plasma membrane has been studied. Using [3 2P]-NAD, the activation by NAD was correlated with the radiolabeling of the stimulatory guanosine triphosphate (GTP) binding protein Gsa. Further characterization demonstrated that the modification occurred only in the presence of G-protein activators and that arginine residue(s) were modified by ADP-ribose by the action of a mono-… more
Date: December 1993
Creator: Coyle, Donna L. (Donna Lynn)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Analysis of Human Transfer RNA Gene Heteroclusters

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… more
Date: December 1986
Creator: Chang, Yung-Nien
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Partner: UNT Libraries
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Nucleotide Inhibition of Glyoxalase II

Description: The glyoxalase system mediates the conversion of methylglyoxal, a toxic ketoaldehyde, to D-lactic acid. The system is composed of two enzymes, glyoxalase I (Glo-I) and glyoxalase II (Glo-II), and exhibits an absolute requirement for a catalytic quantity of glutathione (GSH). Glo-I catalyzes the isomerization of a hemithioacetal, formed non-enzymatically from methylglyoxal and GSH, to the corresponding a -D-hydroxyacid thioester, s-D-lactoylglutathione (SLG). Glo-II catalyzes the irreversible br… more
Date: May 1999
Creator: Gillis, Glen S
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Conformational Studies of Myosin and Actin with Calibrated Resonance Energy Transfer

Description: Resonance energy transfer was employed to study the conformational changes of actomyosin during ATP hydrolysis. To calibrate the technique, the parameters for resonance energy transfer were defined. With conformational searching algorithms to predict probe orientation, the distances measured by resonance energy transfer are highly consistent with the atomic models, which verified the accuracy and feasibility of resonance energy transfer for structural studies of proteins and oligonucleotides. … more
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Date: May 2000
Creator: Xu, Jin
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Partner: UNT Libraries
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Fluorescence labeling and computational analysis of the strut of myosin's 50 kDa cleft.

Description: In order to understand the structural changes in myosin S1, fluorescence polarization and computational dynamics simulations were used. Dynamics simulations on the S1 motor domain indicated that significant flexibility was present throughout the molecular model. The constrained opening versus closing of the 50 kDa cleft appeared to induce opposite directions of movement in the lever arm. A sequence called the "strut" which traverses the 50 kDa cleft and may play an important role in positioning… more
Date: August 2007
Creator: Gawalapu, Ravi Kumar
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Preparation and Characterization of Model Conjugates for the Study of Proteins Modified by ADP-ribose

Description: Modification of proteins by ADP-ribose has been shown to be a versatile modification with respect to the amino acid side chain. The results described here will allow the study of the biological importance of ADP-ribose glycation and also allow differentiation on crude extracts between enzymatic modifications from protein ADP-ribose glycation that can occur due to the presence of NAD glycohydrolases.
Date: August 1992
Creator: Cervantes-Laurean, Daniel
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Partner: UNT Libraries
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