Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.6.1.44 (AGT)
 770 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of enzymes of glycine and alanine synthesis (glutamate-pyruvate aminotransferase, aspartate-beta-decarboxylase, threonine aldolase, serine hydroxymethyltransferase, alanine-glyoxylate aminotransferase, aspartate aminotransferase) is studied in haemolymph, fat body, fibroin and sericine divisions of silk gland of silkworm Bombyx mori at terminal period of larva development. Alanine-glyoxylate aminotransferase activity in fibroin division of silk gland (34,6 mu mole of glycine/mg of protein/min-10(-3)), alanine aminotransferase--in sericine division (36,0 mu mole of alanine/mg of protein/min-10(-3)) aspartate aminotransferase 27,3 mu mole of glutamic acid/mg of protein/min-10(-3)) and alanine aminotransferase (35,8 mu mole of alanine/mg of protein/min-10(-3)) on fat body. The ratio of alanine-glyoxylate aminotransferase/glutamate-pyruvate aminotransferase activities in posterior division of silk gland is near to glycine/alanine ratio in silk fibroin. The character of the enzymes activity in silkworm tissues correlates with the silk formation rate.
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PMID:[Glycine and alanine synthesis enzymes in the tissues of the silkworm during its development]. 99 78

It is shown by fluorescence spectroscopy that the post-activated form of neocarzinostatin chromophore (NCSi-glu) can form stable complexes with single-site oligonucleotides (SSOs) featuring sequences known to be involved in double stranded (AGC.GCT, AGT.ACT, AGA.TCT, ACA.TGT) or single stranded (AGG.CCT) cleavage (attacked residues in bold). Furthermore, the same SSOs form cleavage productive complexes with native neocarzinostatin chromophore (NCS chrom) over a similar concentration range. The productive complexes yield damage similar to that observed if the same sequence is part of a longer DNA piece. Previously identified double stranded site sequences ATT.AAT and TAT.ATA are shown to contain overlapping attack sites. Binding order preference derived from fluorescence quenching experiments for NCSi-glu is consistent with constants derived by quantitative cleavage affinity binding experiments with NCS chrom. This confirms the similarity in interactions between the NCSi-glu and NCS chrom and justifies the use of NCSi-glu as a stable analog of NCS chrom.
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PMID:Binding and cleavage characteristics of the complexes formed between the neocarzinostatin chromophore and single site containing oligonucleotides. 758 49

The ability of O(6)-benzylguanine (BG) to inactivate alkyltransferase (AGT) to potentiate the antitumor efficacy of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) is being tested in clinical trials. As of now, there are no examples of acquired resistance to BG+BCNU in the clinical setting. However, we hypothesized that genetically unstable tumors might develop resistance to the combination after repeated drug-exposures to achieve therapeutic efficacy. To evaluate this possibility, we treated three colon cancer cell lines that are either proficient in mismatch repair (MMR) [SW480 (MMR wild type)] or deficient in MMR [HCT116 (hMLH1 mutant) and HCT15 (hMSH6 mutant)] with three cycles of BG+BCNU. After drug-treatments, HCT116 and HCT15 were completely resistant to BG-potentiated cytotoxicity of BCNU. In these two cell lines, the acquired BG resistance resulted from two de novo and different mutations at amino acid 165 in AGT: 165-lysine (K) to glutamic acid (E) (K165E in HCT116), and 165-lysine to asparagine (N) (K165N in HCT15). Both K165-mutated AGTs had markedly decreased enzymatic activity because of unstable AGT protein but were remarkably resistant to BG inactivation. FISH analysis showed that only one copy of MGMT gene exists in HCT116 cells, and the status of promoter methylation of MGMT in HCT15 showed that one allele of the MGMT promoter has an aberrant methylation. Thus, the MGMT gene expressing AGT either from one copy (HCT116) or from unmethylated allele (HCT15) was mutated because of the exposure to BG+BCNU in these two MMR-deficient cell lines. Conversely, MMR-proficient SW480 cells, treated with three cycles of BG+BCNU, maintained wt AGT and the sensitivity to BG-potentiated BCNU-cytotoxicity. To confirm that K165-mutated AGT proteins were responsible for resistance to BG+BCNU, we transfected K165E and K165N MGMT cDNAs into Chinese hampster ovary (CHO) cells. Transfected CHO cells had low AGT activity but increased IC(50) for either BCNU or temozolomide (TMZ), compared with parental CHO cells. BG did not potentiate the cytotoxicity of these two alkylating agents at concentrations up to 200 microM; in contrast, BG, at 25 microM, sensitized CHO-AGT (transfected with wt MGMT cDNA) cells to BCNU or TMZ-cytotoxicity by 3-4 fold. These results suggest that K165 AGT mutants arising in MMR-deficient tumor cells after treatment with chemotherapeutic agents are both resistant to BG-inactivation and are active in the repair of alkylated DNA adducts.
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PMID:Chemotherapy-induced O(6)-benzylguanine-resistant alkyltransferase mutations in mismatch-deficient colon cancer. 1203 16

Osteogenesis imperfecta (OI) types I-V have been inherited in an autosomal dominant pattern. OI type I is associated with mutations in COL1A1 mostly due to a null allele. OI types II-IV are associated with mutations in COL1A1 or COL1A2 and mostly are due to glycine substitutions. It has been suggested that the effect of glycine substitutions is position specific, and the substitution of glycine by serine has much less lethal effect than the substitutions by valine, aspartic acid, glutamic acid, arginine and cysteine. We report identification of c.3064G>A, GGT>AGT, Gly1022Ser (Gly(844) --> Ser844 in triple helix) in exon 43 of the COL1A1 gene in an 8-year-old girl with OI type III. Our report provides evidence that at triple helix glycine residue 844 (p.Gly1022), a glycine substitution by serine can result in OI type III but not a lethal outcome.
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PMID:Identification of a missense mutation of c.3064G>A, Gly1022Ser in exon 43 of COL1A1 gene in a girl with osteogenesis imperfecta type III. 2307 83