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Query: EC:1.2.1.13 (
glyceraldehyde-3-phosphate dehydrogenase
)
6,511
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Chloroplast NADP-linked
glyceraldehyde-3-phosphate dehydrogenase
was resolved into three forms that differed in molecular weight: (a) larger than or equal to 1.5 million; (b) 600,000; and (c) less than or equal to 100,000. After preincubation with an effector (ATP, NADPH, or Pi) the activity of forms a and c was unaffected, whereas the activity of b, the regulatory form, was increased 10-fold. Activation was accompanied by the exposure of previously hidden sulfhydryl groups. The rate of activation was slower than the rate of catalysis and resulted in a lag phase during the measurement of activity when the enzyme was preincubated in the absence of an effector. The addition of one of several compounds as a second effector (at a concentration which itself was nonactivating) in the presence of a first effector enhanced activation by lowering the concentration of the first effector required for half-maximal activation (Pi constant/ATP or NADPH varied; ATP or NADPH constant/Pi varied). Other combinations of effectors caused little change in activity (ATP constant/NADPH varied; NADPH constant/ATP varied).
Glyceraldehyde
3-phosphate added as a second effector induced contrasting changes: an increase in the ATP-mediated activation and a decrease in the NADPH-mediated activation. The results are consistent with the view that the products of the photochemical reactions of chloroplasts, ATP, and NADPH, in conjunction with other metabolites, regulate the activity of
glyceraldehyde-3-phosphate dehydrogenase
in the photosynthetic assimilation of CO2.
...
PMID:Studies on the regulation of chloroplast NADP-linked glyceraldehyde-3-phosphate dehydrogenase. 1 Feb 97
Glyceraldehyde
-phosphate dehydrogenase (D-glyceraldehyde-3-phosphate : NADP+ oxidoreductase (phosphorylating),
EC 1.2.1.13
) from spinach chloroplasts is a polymeric protein of approx. 600,000 daltons and sodium dodecyl sulphate gel electrophoresis shows that it consists of two subunits of molecular weight 43,000 and 37,000. Comparison of amino acid analyses and tryptic peptide maps indicates that the two subunits have a different primary structure. The native enzyme contains 0.5 mol of NADP+ and 0.5 mol of NAD+ per protomer of 80,000 daltons, no reduced pyridine nucleotides have been detected. Almost complete inactivation is obtained by reaction of two cysteinyl residues per 80,000 daltons with tetrathionate or iodo[14C2]acetic acid; since the same amount of radioactivity is incorporated in the two subunits it is likely that they are both essential for the catalytic activity. Charcoal stripping of native glyceraldehyde-phosphate dehydrogenase produces an apoprotein which still retains most of the enzymatic activity but, unlike the holoenzyme, is gradually inactivated by storage at 4 degrees C and does not react with iodoacetate under the same conditions in which the holoenzyme is completely inactivated.
...
PMID:Subunit structure and activity of glyceraldehyde-3-phosphate dehydrogenase from spinach chloroplasts. 2 61
Inactivation of apo-
glyceraldehyde-3-phosphate dehydrogenase
from rat skeletal muscle in the presence of butanedione is the result of modification of one arginyl residue per subunit of the tetrameric enzyme molecule. The loss of activity follows pseudo-first-order kinetics. NAD+ increases the apparent first-order rate constant of inactivation. The effect of NAD+ on the enzyme inactivation is cooperative (Hill coefficient = 2.3--3.2).
Glyceraldehyde
3-phosphate protected the holoenzyme against inactivation, decreasing the rate constant of the reaction. At saturating concentrations of substrate the protection was complete. The Hill plot demonstrates that the effect is cooperative. This suggests that subunit interactions in the tetrameric holoenzyme molecule may affect the reactivity of the essential arginyl residues. In contrast, glyceraldehyde 3-phosphate had no effect on the rate of inactivation of the apoenzyme in the presence of butanedione. 100 mM inorganic phosphate protected both the apoenzyme and holoenzyme against inactivation. The involvement of the microenvironment of the arginyl residues in the functionally important conformational changes of the enzyme is discussed.
...
PMID:The role of arginine residues in the function of D-glyceraldehyde-3-phosphate dehydrogenase. 21 10
When chicken breast muscle was homogenized in water, approximately 86% of the
glyceraldehyde-3-phosphate dehydrogenase
was associated with the particulate fraction. The enzyme was solubilized by increasing pH with a very marked increase in the pH range of 6.9 to 7.1. At low ionic strength (about 0.015), approximately 50% of the enzyme is solubilized at pH 7.5 and above. Increasing ionic strength also led to increased solubilization. In addition, there was a specific cation effect with Ca2+ greater than Mg2+ greater than K+ greater than Na+ at a constant ionic strength.
Glyceraldehyde
3-phosphate and 2,3-bisphosphoglycerate were effective in partially solubilizing the enzyme. Solubilized
glyceraldehyde-3-phosphate dehydrogenase
can rebind to the particulate fraction of the homogenized muscle. The soluble form of the enzyme has a higher V and a higher Km (glyceraldehyde-3-phosphate) than the enzyme bound to the particulate fraction.
...
PMID:Association of glyceraldehyde-3-phosphate dehydrogenase with the particulate fraction of chicken skeletal muscle. 24 Jun 91
The binding of a spin-labeled AMP analog to tetrameric
glyceraldehyde-3-phosphate dehydrogenase
from rabbit muscle is described. The spin label, perdeuterated and 15N-substituted 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, was attached to C-8 of AMP (C8-SL-AMP). Up to 8 equivalents of C8-SL-AMP bind per enzyme tetramer, i.e., 2 per monomer. Combining sites are the adenine subsite of the coenzyme-binding domain and the phosphate site.
Glyceraldehyde
3-phosphate causes a conformational change in the enzyme that brings C8-SL-AMP molecules bound to adjacent R-axis-related subunits closer to one another by 0.2-0.3 nm and allows for spin-spin interaction between the nitroxide radicals. Similar, but less pronounced structural changes take place upon lowering the pH from 8 to 7. Addition of a single equivalent of NAD+ to a complex of the enzyme with 7.6 equivalents of C8-SL-AMP leads to the release of almost 4 C8-SL-AMP molecules. This supports our previous findings that binding of just one NAD+ molecule induces conformational changes in all four subunits.
...
PMID:Interaction of glyceraldehyde-3-phosphate dehydrogenase with AMP as studied by means of a spin-labeled analog. 255 43
Objective
: Recently, the role of long non-coding RNAs (lncRNAs) in hepatocellular carcinoma (HCC) has been assessed. Our research was determined to investigate the impacts of lncRNA TP73-AS1 on radioresistance of HCC by modulating PTEN/Akt signaling pathway.
Methods
: Expression of TP73-AS1 in HCC tissues and cells was detected using reverse transcription quantitative polymerase chain reaction (RT-qPCR). The HCC cells were conducted with different doses of irradiation, then the survival, colony formation and apoptosis were determined by a series of assays. The HCC cell line with a higher expression of TP73-AS1 was transfected with TP73-AS1-siRNA and X-rayed, the expression of TP73-AS1, cell survival, radiosensitivity, and apoptosis were evaluated. Subcutaneous tumorigenesis in nude mice was adopted to record the size of tumors before and after the radiation. RT-qPCR and Western blot analysis were used to clarify the activation of PTEN/Akt signaling pathway.
Results
: TP73-AS1 was highly expressed in HCC tissues and cells. With the increasing dose of radiation, the relative proliferation activity and survival fraction (SF) of HCC cells was gradually reduced, while the total apoptosis rate was gradually elevated. TP73-AS1 knockdown promoted radiosensitivity and apoptosis, repressed cell proliferation, making it an inhibitor of tumor in HCC. Moreover, reduced TP73-AS1 was able to decline the phosphorylation of Akt and increase the expression of PTEN in HCC. Down-regulated TP73-AS1 could repress tumorigenesis by promoting radiosensitivity in nude mice with HCC.
Conclusion
: Our study suggests that lncRNA TP73-AS1 was highly expressed in HCC and participated in radioresistance of HCC via PTEN/Akt signaling pathway.
Abbreviations:
lncRNAs: long non-coding RNAs; lncRNAs: HCC: hepatocellular carcinoma; RT-qPCR: reverse transcription quantitative polymerase chain reaction; survival fraction: SF; lncRNA TP73-AS1: LncRNA P73 antisense RNA 1T; PTEN: Phosphatase and tensin homologue; Akt: Protein kinase B; P13K: phosphatidylinositol 3-kinase; TNM: tumor, node and metastasis; ACJJ: American Joint Committee on Cancer; FBS: fetal bovine serum; EDTA: ethylene diamine tetraacetic acid; NC: negative control; DMEM: Dulbecco's modified Eagle medium; OD: optical density; PE: Plating efficiency; FITC/PI: fluoresceine isothiocyanate/propidium iodide; PBS: phosphate buffered solution;
GAPDH
:
Glyceraldehyde
phosphate dehydrogenase; ANOVA: one-way analysis of variance; LSD-t: least significant difference test.
...
PMID:Down-regulated lncRNA TP73-AS1 reduces radioresistance in hepatocellular carcinoma via the PTEN/Akt signaling pathway. 3156 1