Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The coenzyme pyridoxal phosphate and its analogs were tested for inhibition of the self-splicing of primary transcripts of the phage T4 thymidylate synthase gene (td). Of all compounds examined, the pyridoxal phosphate was the most potent inhibitor and the order of inhibitory efficiency for compounds tested was as follows: pyridoxal phosphate > pyridoxal > pyridoxine > pyridoxamine > pyridoxic acid. Increasing Mg2+ concentration up to 14 mM overcame the suppression of self-splicing by pyridoxal phosphate up to 95% of the level of normal splicing, implying its interference with effective catalysis of Mg2+. The kinetic analysis demonstrated that pyridoxal phosphate acts as a mixed type noncompetitive inhibitor for the td intron RNA with a K(i) of 11.8 mM. The specificity of the splicing inhibition by pyridoxal phosphate is predominantly due to increases in K(m) and decreases in V(max) values.
Mol Cell Biochem 2005 Dec
PMID:Pyridoxal phosphate inhibits the group I intron splicing. 1631 1

We studied the effects of phosphates on the expression of the human tissue-nonspecific alkaline phosphatase (TNSALP) gene and phosphate-regulating genes in short-term cultures of human osteoblastic osteosarcoma cell lines. When human osteosarcoma cell lines, SaOS-2, MG-63, and U(2)OS were cultured with 10 mM inorganic sodium dihydrogenphosphate, 10 mM beta-glycerophosphate, 250 microM pyridoxal phosphate, or 100 microM inorganic pyrophosphate, enzymatic activity of alkaline phosphatase began to increase at 72 h after addition of sodium dihydrogenphosphate and beta-glycerophosphate in SaOS-2 cells. Pyridoxal phosphate and pyrophosphate did not induce alkaline phosphatase activity. U(2)OS cells slightly reacted to beta-glycerophosphate, but MG-63 cells did not react on exposure to phosphates. In SaOS-2 cells, TNSALP mRNA measured by real-time RT-PCR reached a peak level at 72 h after the addition of beta-glycerophosphate. PHEX and MEPE mRNAs were also induced by beta-glycerophosphate. These results suggest that TNSALP, PHEX and MEPE were concordantly induced by beta-glycerophosphate on mineralisation.
Mol Cell Biochem 2006 Jan
PMID:Effects of phosphates on the expression of tissue-nonspecific alkaline phosphatase gene and phosphate-regulating genes in short-term cultures of human osteosarcoma cell lines. 1631 17

Alanine:glyoxylate aminotransferase (AGT) is a liver peroxisomal enzyme, deficiency of which results in primary hyperoxaluria type 1 (PH1). More than 65 PH1-related mutations are now documented in the AGT gene (AGXT), of which about 50% are missense. We have generated a spectrum of 15 missense changes including the most common PH1 mutation, G170R, and expressed them on the appropriate background of the major or minor allele, in an Escherichia coli overexpression system and in a rabbit reticulocyte transcription/translation system. We have investigated their effects on enzyme activity, dimerization, aggregation, and turnover. The effect of pyridoxal phosphate (PLP) on dimerization and stability was also investigated. Although all 15 mutant AGTs were expressed as intact proteins in E. coli, only three: G41R and G41V on the major allele, and the common mutation G170R, resulted in significant amounts of enzymatic activity. Dimerization failure was a frequent observation (13/15) except for G41V and D183N. Dimerization was poor with S187F but was substantially improved with PLP. Proteasome-mediated protein degradation was observed for all the mutations except G41R on the major allele, G41V, D183N, G170R, and S218L. Increases in the stability of the mutant enzymes in the presence of PLP were small; however, G41R on the minor allele showed a direct relationship between its half life and the concentration of PLP. The minor allele AGT product and many of the mutants were subject to a limited non-proteasomal proteolytic cleavage when ATP was depleted.
Mol Genet Metab 2006 Dec
PMID:Consequences of missense mutations for dimerization and turnover of alanine:glyoxylate aminotransferase: study of a spectrum of mutations. 1697 Nov 51

A novel DNA modification system by sulfur (S) in Streptomyces lividans 66 was reported to be encoded by a cluster of five genes designated dndA-E [Zhou, X., He, X., Liang, J., Li, A., Xu, T., Kieser, T., Helmann, J. D., and Deng, Z. (2005) Mol. Microbiol. 57, 1428-1438]. The dndA gene was cloned and the protein product expressed in Escherichia coli, purified to homogeneity, and characterized as a homodimeric protein of ca. 91 kDa. Purified DndA has a yellow color and UV-visible spectra characteristic of a pyridoxal phosphate-containing enzyme and was proven to be a cysteine desulfurase able to catalyze removal of elemental S atoms from l-cysteine to produce l-alanine with substrate specificity similar to that of E. coli IscS. DndC was also purified to homogeneity and found to contain a 4Fe-4S cluster by spectral analysis and have obvious ATP pyrophosphatase activity. DndA could catalyze iron-sulfur cluster assembly by activation of apo-Fe DndC protein prepared by removal of its iron-sulfur cluster using alpha,alpha'-dipyridyl. A mutated DndA, with serine substituted for cysteine at position 327, which was confirmed to have lost its corresponding cysteine desulfurase activity, also lost its ability to reactivate the apo-Fe DndC. The likely involvement of an interaction between DndA and DndC in the biochemical pathway for the unusual site-specific DNA modification in S. lividans 66 is discussed.
 ...
PMID:A novel DNA modification by sulfur: DndA is a NifS-like cysteine desulfurase capable of assembling DndC as an iron-sulfur cluster protein in Streptomyces lividans. 1746 5

Carbonyls generated by autoxidation of carbohydrates or lipid peroxidation have been implicated in advanced glycation end product (AGE) formation in tissues adversely affected by diabetes complications. Tissue AGE and associated pathology have been decreased by vitamin B(1)/B(6) in trials involving diabetic animal models. To understand the molecular cytoprotective mechanisms involved, the effects of B(1)/B(6) vitamers against cytotoxicity induced by AGE/advanced lipid end product (ALE) carbonyl precursors (glyoxal/acrolein) have been compared to cytotoxicity induced by oxidative stress (hydroperoxide) or mitochondrial toxins (cyanide/copper). Thiamin was found to be best at preventing cell death induced by carbonyl stress and mitochondrial toxins but not oxidative stress cell death suggesting that thiamin pyrophosphate restored pyruvate and alpha-ketoglutarate dehydrogenases inhibited by mitochondrial toxicity. However, B(6) vitamers were most effective at preventing oxidative stress or lipid peroxidation cytotoxicity suggesting that pyridoxal or pyridoxal phosphate were antioxidants and/or Fe/Cu chelators. A therapeutic vitamin cocktail could provide maximal prevention against carbonyl stress toxicity associated with diabetic complications.
Mol Nutr Food Res 2008 Mar
PMID:Preventing cell death induced by carbonyl stress, oxidative stress or mitochondrial toxins with vitamin B anti-AGE agents. 1791 69

We present a patient with severe pyridox(am)ine 5'-phosphate oxidase deficiency and homozygosity for a novel nonsense-mutation, p.A174X, in the PNPO gene who died with pyridoxal phosphate (PLP) treatment despite initial clinical recovery. He presented neonatally, with the classical clinical symptoms of the disease. Increase of urinary vanillactate was the first biochemical factor of alert. Amino acid and neurotransmitter analysis in CSF indicated reduced activity of several PLP-dependent enzymes. The diagnosis was confirmed by mutational studies. From this and the other reported patients it may be concluded that the administration of PLP should not be delayed until the complete biochemical evidence is obtained.
Mol Genet Metab 2008 Feb
PMID:A new fatal case of pyridox(am)ine 5'-phosphate oxidase (PNPO) deficiency. 1802 16

Alanine:glyoxylate aminotransferase (AGT) is a liver peroxisomal enzyme whose deficiency results in primary hyperoxaluria type 1 (PH1). More than 75 PH1 mutations are now documented in the AGT gene (AGXT), of which about 50% are missense. We have previously demonstrated that many such mutants expressed by transcription/translation are subject to generalized degradation by the proteasome and a specific limited trimming by an endogenous ATP-independent protease activity. Here, we report the results of partial digestion using trypsin as a mimic for the endogenous non-proteasomal protease and the use of N-terminal protein sequencing to determine the sensitive site. Partial trypsin digestion also provided an indicator of proper folding of the mutant enzyme. For selected mutations the sensitivity to trypsin could be ameliorated by addition of pyridoxal phosphate or aminooxy acetic acid as specific pharmacological chaperones.
Mol Genet Metab 2008 Jul
PMID:Partial trypsin digestion as an indicator of mis-folding of mutant alanine:glyoxylate aminotransferase and chaperone effects of specific ligands. Study of a spectrum of missense mutants. 1844 74

Glutamate decarboxylase (GAD) is the rate-limiting enzyme in the synthesis of gamma-aminobutyric acid (GABA), the most important inhibitory neurotransmitter in central nervous system (CNS). Two homologous forms of GAD encoded by separate genes have been identified in mammalian brain, with molecular weight of 65 kDa (GAD65) and 67 kDa (GAD67). In the present study, four novel GAD67 transcripts produced by alternative splicing and polyadenlyation were cloned from rat testis. These novel GAD67 transcripts were widely expressed in non-neuronal tissues. During rat testis maturation, their expression level showed a time dependent change. These transcripts were predicted to synthesis of GAD proteins truncated of the binding site for pyridoxal phosphate, an essential cofactor, therefore cannot function as a decarboxylase. Thus, post-transcriptional processing mechanism as alternative splicing and polyadenlyation may play a crucial role in regulating rat GAD67 gene expression.
Mol Biol Rep 2009 Jul
PMID:Utilization of an intron located polyadenlyation site resulted in four novel glutamate decarboxylase transcripts. 1875 93

LL-Diaminopimelate aminotransferase (LL-DAP-AT), a pyridoxal phosphate (PLP)-dependent enzyme in the lysine biosynthetic pathways of plants and Chlamydia, is a potential target for the development of herbicides or antibiotics. This homodimeric enzyme converts L-tetrahydrodipicolinic acid (THDP) directly to LL-DAP using L-glutamate as the source of the amino group. Earlier, we described the 3D structures of native and malate-bound LL-DAP-AT from Arabidopsis thaliana (AtDAP-AT). Seven additional crystal structures of AtDAP-AT and its variants are reported here as part of an investigation into the mechanism of substrate recognition and catalysis. Two structures are of AtDAP-AT with reduced external aldimine analogues: N-(5'-phosphopyridoxyl)-L-glutamate (PLP-Glu) and N-(5'-phosphopyridoxyl)- LL-Diaminopimelate (PLP-DAP) bound in the active site. Surprisingly, they reveal that both L-glutamate and LL-DAP are recognized in a very similar fashion by the same sets of amino acid residues; both molecules adopt twisted V-shaped conformations. With both substrates, the alpha-carboxylates are bound in a salt bridge with Arg404, whereas the distal carboxylates are recognized via hydrogen bonds to the well-conserved side chains of Tyr37, Tyr125 and Lys129. The distal C(epsilon) amino group of LL-DAP is specifically recognized by several non-covalent interactions with residues from the other subunit (Asn309*, Tyr94*, Gly95*, and Glu97* (Amino acid designators followed by an asterisk (*) indicate that the residues originate in the other subunit of the dimer)) and by three bound water molecules. Two catalytically inactive variants of AtDAP-AT were created via site-directed mutagenesis of the active site lysine (K270N and K270Q). The structures of these variants permitted the observation of the unreduced external aldimines of PLP with L-glutamate and with LL-DAP in the active site, and revealed differences in the torsion angle about the PLP-substrate bond. Lastly, an apo-AtDAP-AT structure missing PLP revealed details of conformational changes induced by PLP binding and substrate entry into the active site.
J Mol Biol 2008 Dec 31
PMID:Mechanism of substrate recognition and PLP-induced conformational changes in LL-diaminopimelate aminotransferase from Arabidopsis thaliana. 1895 95

L-DOPA decarboxylase (DDC) is a pyridoxal 5-phosphate (PLP)-dependent enzyme that catalyses the decarboxylation of L-DOPA to dopamine. Dopamine (DA) has been found to be a regulating factor of the proliferation and differentiation of different leukocyte subtypes. In the present study, we report the expression of the gene that codes for the L-DOPA decarboxylase in human peripheral leukocytes and in T-lymphocytes, as well as the simultaneous detection of both neural and non-neural type DDC mRNA in the cellular components of this specialized connective tissue type. Furthermore, we have detected the neural type DDC transcript which lacks exon 3 and the alternative 37 kD alt-DDC protein isoform which lacks exons 10-15 but includes an alternative exon 10 in human peripheral leukocytes. Treatment of white blood cells with Triton X-114 resulted in the recovery of DDC in the detergent enriched and highly hydrophobic phases, suggesting association of DDC molecules with membranes in the studied cells. Enzymatic activity experiments revealed that DDC is active towards the decarboxylation of L-DOPA. The expression of enzymatically active DDC in human leukocytes could indicate a cross-talk between the nervous and the immune systems and raises new questions about the regulatory role of DDC in immune responses.
Blood Cells Mol Dis
PMID:Expression of enzymatically active L-DOPA decarboxylase in human peripheral leukocytes. 1904 Dec 69


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>