UNT Libraries - 51 Matching Results

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open access

O-Acetylserine Sulhydralase-A from Salmonella typhimurium LT-2: Thermodynamic Properties and SPectral Identification of Intermediates

Description: O-Acetylserine Sulfhydrylase (OASS) is a pyridoxal phosphate enzyme that catalyzes the reaction of O-acetyl-Lserine with sulfide to give L-cysteine. OASS is present as two isoforms, designated -A and -B. The kinetic mechanism of OASS-A is well known and there is also much known concerning the acid-base chemistry of the enzyme. However, little is known concerning the location of the rate determining steps, the sequencing of chemical steps that occur at the active site, or the nature of the rate … more
Date: August 1993
Creator: Simmons, James Walter
open access

N-Acylethanolamine Metabolism During Seed Germination: Molecular Identification of a Functional N-Acylethanolamine Amidohydrolase

Description: N-Acylethanolamines (NAEs) are endogenous lipid metabolites that occur in a variety of dry seeds, and their levels decline rapidly during the first few hours of imbibition (Chapman et al., 1999, Plant Physiol., 120:1157-1164). Biochemical studies supported the existence of an NAE amidohydrolase activity in seeds and seedlings, and efforts were directed toward identification of DNA sequences encoding this enzyme. Mammalian tissues metabolize NAEs via an amidase enzyme designated fatty acid amid… more
Date: August 2004
Creator: Shrestha, Rhidaya
open access

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
open access

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)
open access

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
open access

Application of Synthetic Peptides as Substrates for Reversible Phosphorylation

Description: Two highly homologous synthetic peptides MLC(3-13) (K-R-A-K-A-K-T-TK-K-R-G) and MLC(5-13) (A-K-A-K-T-T-K-K-R-G) corresponding to the amino terminal amino acid sequence of smooth muscle myosin light chain were utilized as substrates for protein kinase C purified from murine lymphosarcoma tumors to determine the role of the primary amino acid sequence of protein kinase C substrates in defining the lipid (phosphatidyl serine and diacylglycerol) requirements for the activation of the enzyme. Remova… more
Date: August 1992
Creator: Abukhalaf, Imad Kazem
open access

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)
open access

Characterization of a Human 28S Ribosomal RNA Retropseudogene and Other Repetitive DNA Sequence Elements Isolated from a Human X Chromosome-Specific Library

Description: Three genomic clones encompassing human DNA segments (designated LhX-3, LhX-4, and LhX5) were isolated from an X chromosome-specific library and subjected to analysis by physical mapping and DNA sequencing. It was found that these three clones are very rich in repetitive DNA sequence elements and retropseudogenes.
Date: May 1994
Creator: Wang, Suyue

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
open access

Cottonseed Microsomal N-Acylphosphatidylethanolamine Synthase: Identification, Purification and Biochemical Characterization of a Unique Acyltransferase

Description: N-Acylphosphatidylethanoiamine (NAPE) is synthesized in the microsomes of cotton seedlings by a mechanism that is possibly unique to plants, the ATP-, Ca2+-, and CoA-independent acylation ofphosphatidylethanolamine (PE) with unesterified free fatty acids (FFAs), catalyzed by NAPE synthase. A photoreactive free fatty acid analogue, 12-[(4- azidosalicyl)amino]dodecanoic acid (ASD), and its 125I-labeled derivative acted as substrates for the NAPE synthase enzyme.
Date: December 1998
Creator: McAndrew, Rosemary S. (Rosemary Smith)
open access

Dependence of the Kinetic Mechanism of Adenosine 3',5'-Monophosphate Dependent Protein Kinase Catalytic Subunit in the Direction of Magnesium Adenosine 5'-Diphosphate Phosphorylation on pH and the Concentration of Free Magnesium Ions

Description: To define the overall kinetic and chemical mechanism of adenosine 3',5'-monophosphate dependent protein kinase catalytic subunit, the mechanism in the direction of MgADP phosphorylation was determined, using studies of initial velocity in the absence and presence of dead-end inhibitors. The kinetic mechanism was determined as a function of uncomplexed Mg^2+ (Mg_f) at pH 7.2 and as a function of pH at low (0.5 mM) Mg_f. At pH 7.2 data are consistent with a random kinetic mechanism in the directi… more
Date: December 1992
Creator: Qamar, Raheel
open access

Development of Enabling Technologies to Visualize the Plant Lipidome

Description: Improvements in mass spectrometry (MS)-based strategies for characterizing the plant lipidome through quantitative and qualitative approaches such as shotgun lipidomics have substantially enhanced our understanding of the structural diversity and functional complexity of plant lipids. However, most of these approaches require chemical extractions that result in the loss of the original spatial context and cellular compartmentation for these compounds. To address this current limitation, severa… more
Date: August 2013
Creator: Horn, Patrick J.
open access

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
open access

Fumarate Activation and Kinetic Solvent Isotope Effects as Probes of the NAD-Malic Enzyme Reaction

Description: The kinetic mechanism of activation of the NAD-malic enzyme by fumarate and the transition state structure for the oxidation malate for the NAD-malic enzyme reaction have been studied. Fumarate exerts its activating effect by decreasing the off-rate for malate from the E:Mg:malate and E:Mg:NAD:malate complexes. The activation by fumarate results in a decrease in K_imalate and an increase in V/K_malate by about 2-fold, while the maximum velocity remains constant. A discrimination exists between … more
Date: December 1992
Creator: Lai, Chung-Jeng
open access

Function of the ENOD8 gene in nodules of Medicago truncatula.

Description: To elaborate on the function(s) of the ENOD8 gene in the nodules of M. truncatula, several different experimental approaches were used. A census of the ENOD8 genes was first completed indicating that only ENOD8.1 (nt10554-12564 of GenBank AF463407) is highly expressed in nodule tissues. A maltose binding protein-ENOD8 fusion protein was made with an E. coli recombinant system. A variety of biochemical assays were undertaken with the MBP-ENOD8 recombinant protein expressed in E. coli, which did … more
Date: December 2006
Creator: Coque, Laurent
open access

Functional Characterization of Mtnip/latd’s Biochemical and Biological Function

Description: Symbiotic nitrogen fixation occurs in plants harboring nitrogen-fixing bacteria within the plant tissue. The most widely studied association is between the legumes and rhizobia. In this relationship the plant (legumes) provides the bacteria (rhizobia) with reduced carbon derived from photosynthesis in exchange for reduced atmospheric nitrogen. This allows the plant to survive in soil, which is low in available of nitrogen. Rhizobia infect and enter plant root and reside in organs known as nodul… more
Date: December 2013
Creator: Bagchi, Rammyani
open access

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
open access

Functional Significance of Sympathetic Fiber Ingrowth in the Habenula

Description: The physiological significance of noradrenergic sympathohabenular ingrowth following medial septal lesions was investigated. Following septal lesions, sympathetic fibers originating in the superior cervical ganglia are known to sprout into the medial habenular nuclei, and into the hippocampal formation. Previous work involving sympathohippocampal ingrowth showed that firing rates in septal animals with no ingrowth showed that firing rates in septal animals with no ingrowth were higher than rate… more
Date: August 1986
Creator: Howard, A. Jean (Ava Jean)
open access

Identification and Characterization of an Arabidopsis thaliana Mutant with Tolerance to N-lauroylethanolamine

Description: N-Acylethanolamines (NAEs) are fatty acid derivatives in plants that negatively influence seedling growth. N-Lauroylethanolamine (NAE 12:0), one type of NAE, inhibits root length, increases radial swelling of root tips and reduces root hair numbers in a dose dependent manner in Arabidopis thaliana L. (ecotype Columbia). A forward genetics approach was employed by screening a population of T-DNA “activation-tagged” developed by the Salk Institute lines for NAE resistance to identify potential … more
Date: December 2015
Creator: Adhikari, Bikash
open access

Identification of Endogenous Substrates for ADP-Ribosylation in Rat Liver

Description: Bacterial toxins have been shown to modify animal cell proteins in vivo with ADPR. Animal cells also contain endogenous enzymes that can modify proteins. Indirect evidence for the existence in vivo of rat liver proteins modified by ADPR on arginine residues has been reported previously. Presented here is direct evidence for the existence of ADP-ribosylarginine in rat liver proteins. Proteins were subjected to exhaustive protease digestion and ADP-ribosyl amino acids were isolated by boronate ch… more
Date: May 1992
Creator: Loflin, Paul T. (Paul Tracey)
open access

Identification of Three Symbiosome Targeting Domains in the MtENOD8 Protein and Cell-to-cell MtENOD8 mRNA Movement in Nodules

Description: The model legume, Medicago truncatula, is able to enter into a symbiotic relationship with soil bacteria, known as rhizobia. This relationship involves a carbon for nitrogen exchange in which the plant provides reduced carbon from photosynthesis in exchange for reduced, or “fixed” atmospheric nitrogen, which allows the plant to thrive in nitrogen depleted soils. Rhizobia infect and enter plant root organs, known as nodules, where they reside inside the plant cell in a novel organelle, known a… more
Date: May 2012
Creator: Meckfessel, Matthew Harold
open access

Induced CSF-1 Production and its Effects on C-FMS Transfected Monoblastic U937 Cells

Description: This study examined how the monoblast-like human histiocytic lymphoma cell line U937 can be induced by phorbol 12-myristrate 13-acetate (PMA) to undergo differentiation. In order to study the mechanism of action of CSF-1, a CSF-1 receptor gene (c-fms) was transfected into U937 cells. Exogenous CSF-1 treatment induced an autocrine response in this CSF-1 was determined and all events were shown to be time dependent. CSF-1 stimulation also enhanced proto-oncogene c-jun and c-myc gene expression. … more
Date: August 1992
Creator: Liu, Mu-ya
open access

Kinetic and Chemical Mechanism of 6-phosphogluconate Dehydrogenase from Candida Utilis

Description: A complete initial velocity study of the 6-phosphogluconate dehydrogenase from Candida utilis in both reaction directions suggests a rapid equilibrium random kinetic mechanism with dead-end E:NADP:(ribulose 5-phosphate) and E:NADPH:(6- phosphogluconate) complexes. Initial velocity studies obtained as a function of pH and using NAD as the dinucleotide substrate for the reaction suggest that the 2'-phosphate is critical for productive binding of the dinucleotide substrate. Primary deuterium isoto… more
Date: May 1993
Creator: Berdis, Anthony J. (Anthony Joseph)
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