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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)
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

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

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
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

Studies on ADP-Ribose Polymer Metabolism in Cultured Mammalian Cells Following DNA Damage

Description: ADP-ribose polymer metabolism has been studied in human cells derived from a patient with Glutamyl Ribose Phosphate Storage Disease (GRPSD) and in mouse C3H1OT1/2 cells following oxidative stress induced by hydrogen peroxide (H202 ). It has been postulated that GRPSD resulted from an abnormality in ADP-ribose polymer metabolism. This study has shown that these cells exhibit reduced poly(ADP ribose) polymerase activity which is proposed to result from modification of the enzyme with ribose phosp… more
Date: May 1991
Creator: Maharaj, Geeta
open access

Protein Kinase C Activation in Hyperglycemic Bovine Lens Epithelial Cells

Description: This study demonstrates the presence of protein kinase C activity in both cytosolic and membrane fractions of bovine lens epithelial cells in culture. Protein kinase C activity is similar in normal and hyperglycemic cells. Furthermore, the ability of the enzyme to translocate from the cytosol to the membrane following phorbol ester treatment is unimpeded by hyperglycemic conditions. Moreover, protein kinase C activation had no effect on myoinositol uptake either in normal cells or in cells expo… more
Date: December 1993
Creator: Fan, Wen-Lin
open access

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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