Search results for "Isozyme"
showing 10 items of 102 documents
The Influence of Thiol Reagents on the Isoenzyme Pattern of Plant L+Lactate Dehydrogenase (EC 1.1.1.27)
1978
Summary Lactate dehydrogenase from potato tubers was incubated together with various thiol reagents and the effect on the electrophoretic behavior of its isoenzymes studied. while disulfides, alkylating agents, and H202 did not alter the number and electrophoretic behavior of the isoenzymes of L + LDH, reduced glutathione and 2-mercaptoethanol led to an increase in the number of isoenzymes. The reaction was dependent on concentration and pH. On the other hand, cysteine and cysteamine had no such effect. Results are discussed in view of the possible secondary nature of the plant LDH isoenzymes.
Purification, isolation and characterization of a phosphoglycolate phosphatase isoenzyme from human erythrocytes.
1982
1. Preparation, purification and characterization of a phosphoglycolate phosphatase (PGP) isoenzyme from human erythrocytes was achieved by DEAE-Sepharose CL-6B chromatography and isoelectric focusing using carrier ampholytes, pH 4-6. 2. The isoenzyme has an isoelectric point of 5.00 +/- 0.05 and could be purified 33,000 fold to a specific activity of 32.7 U/mg of protein. It represents the PGP phenotype 1 consisting of a single isoenzyme. 3. The enzyme is composed of two subunits (mol. wt 35,000) which are identical and not connected by SS-bridges. 4. At 4 degrees C the isoenzyme is more stable in the pH range of 7-9 than at acid pH values. 5. Incubation at 30 and 40 degrees C for 4 hr doe…
Cellular and Subcellular Localization of Peroxidase Isoenzymes in Plants and Cell Suspension Cultures from Lupinus polyphyllus
1989
Abstract , leaf protoplasts and cell suspension cultures of Lupinus polyphyllus and isolated vacuoles were studied for cellular and subcellular localization of peroxidase isoenzymes. Isoelectric focusing revealed 16 peroxidase isoenzymes. The basic peroxidase isoenzymes are predominantly localized in the vacuole and, to a minor degree, unbound in the intercellular space. The acidic isoenzymes are cell wall-bound in plants and not detectable in suspension-cultured cells. Large amounts (up to 11.0 U/ml) of a single basic isoenzyme are detectable in the spent medium of cell suspension cultures.
ChemInform Abstract: Cyclooxygenase Inhibitors - Current Status and Future Prospects
2010
Prostaglandins are formed from arachidonic acid by the action of cyclooxygenase and subsequent downstream synthetases. Two closely related forms of the cyclooxygenase have been identified which are now known as COX-1 and COX-2. Both isoenzymes transform arachidonic acid to prostaglandins, but differ in their distribution and their physiological roles. Meanwhile, the responsible genes and their regulation have been clarified. COX-1, the pre-dominantly constitutive form of the enzyme, is expressed throughout the body and performs a number of homeostatic functions such as maintaining normal gastric mucosa and influencing renal blood flow and platelet aggregation. In contrast, the inducible for…
Phenobarbital Induction of UDP-glucosyltransferase Activity in Drosophila melanogaster Meigen
2000
The inducibility of UDP-glucosyltransferase activities towards the exogenous substrates 1-naphthol and 2-naphthol and the endogenous metabolite xanthurenic acid was demonstrated in Drosophila melanogaster Meigen larvae and adults using phenobarbital as an inducer. In adults, a 3.5-fold increase of glucosyltransferase activity toward xanthurenic acid and a 2.0-fold increase of the activity toward exogenous substrates (1-naphthol and 2-naphthol) was found. In larvae, maximum induction of all three UDP-glucosyltransferase activities (2.5-fold and 1.5-fold increase of the activity toward the exogenous and endogenous substrates, respectively) was achieved when insects, reared on solid medium, we…
Comperative studies with Culex pipiens egg rafts. Immunogenetic, electrophoretic and enzymatic analysis of unfertilized, compatible and incompatible …
1973
By applying immunologic, electrophoretic and enzymatic methods, extracts of different raft types of Culex pipiens were analysed. Rafts of the crosses Pa x Pa and Ha x Ha contained four common antigens, while unfertilized rafts of Pa and Ha (no antisera were prepared against them) and rafts of the crosses Og x Og, Og x Pa, and Pa x Og shared three common antigens with the remaining raft extracts. Disk-electrophoresis of raft extracts in acrylamide gel resulted in different electropherograms. Ten protein bands were common to all these raft types. The unfertilized rafts of Pa and Ha yielded three more protein bands, the crosses Pa x Ha and Ha x Pa one more, the crosses Og x Og and Pa x Og thre…
Data Evaluation in Population Genetics and Evolution
1994
Isozymes maybe generated by different enzyme loci (a) (isoenzymes), (b) alleles of a locus (allozymes) or (c) post-translational modifications (secondary isozymes). Differences in isozyme numbers and isoenzyme properties can be used for evolutionary studies. But quantitations of genetic variation among or within populations are obtainable only from allozyme frequencies.
Biochemical characterization of two functional human liver acyl-CoA oxidase isoforms 1a and 1b encoded by a single gene
2007
Abstract Human acyl-CoA oxidase 1 (ACOX1) is a rate-limiting enzyme in peroxisomal fatty acids β-oxidation and its deficiency is associated with a lethal, autosomal recessive disease, called pseudoneonatal-adrenoleukodystrophy. Two mRNA variants, transcribed from a single gene encode ACOX1a or ACOX1b isoforms, respectively. Recently, a mutation in a splice site has been reported [H. Rosewich, H.R. Waterham, R.J. Wanders, S. Ferdinandusse, M. Henneke, D. Hunneman, J. Gartner, Pitfall in metabolic screening in a patient with fatal peroxisomal β-oxidation defect, Neuropediatrics 37 (2006) 95–98.], which results in the defective peroxisomal fatty acids β-oxidation. Here, we show that these mRNA…
Expression and Expressional Control of Nitric Oxide Synthases in Various Cell Types
1995
Publisher Summary Nitric oxide (NO) can produce posttranslational modifications of proteins (via ADP ribosylation) and is capable of destroying parasites and tumor cells by inhibiting iron-containing enzymes or directly interacting with the DNA of these cells. In view of this multitude of functions of NO, it is important to understand how cells accomplish and regulate their NO production. Three isozymes of NOS have been identified, and their protein, cDNA, and genomic DNA structures have been elucidated. In humans NOS I, II, and III are encoded by three different genes, located on chromosomes 12, 17, and 7 respectively. The cDNAs for these enzymes have been isolated. All NOS isozymes oxidiz…
Purification and Characterization of Glutamine Synthetase Isoenzymes from Leaves and Roots of Brassica napus (L.)
1995
Summary The glutamine synthetase enzymes from leaves (GS2) and roots (GSR) of Brassica napus L. have been purified to homogeneity by the application of a three-stage isolation procedure comprising anion-exchange chromatography, adsorption by hydroxylapatite and gel filtration on Sephacryl 5-300 HR. The isoforms of the enzyme show a differential distribution in leaf and root tissues. Elution profiles of hydroxylapatite chromatography showed a distinct behaviour for GS proteins found in leaves and roots. Denaturing SDS-PAGE and Western blot experiments revealed molecular masses of approximately 43.5 and 40.5 kD for GS2 and GSR subunits, respectively. Moreover, kinetic properties determined us…