Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.1.1.37 (malate dehydrogenase)
4,591 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thioredoxin derivatives lacking SH groups such as S,S'-dicarboxymethyl-, dicarboxamidomethyl-thioredoxin and cysteine----serine mutant protein are capable of activating chloroplast NADP malate dehydrogenase and fructose-bisphosphatase when added to enzyme assays together with suboptimal amounts of native thioredoxin. The modified thioredoxins alone are inactive. These findings indicate that protein-protein interactions play a significant role in addition to disulfide/thiol exchange reactions in the light-driven regulation of plant enzymes by the various plant thioredoxins.
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PMID:Non-redox protein interactions in the thioredoxin activation of chloroplast enzymes. 132 Sep 37

This paper reports the purification and the properties of a thioredoxin from the fungus Aspergillus nidulans. This thioredoxin is an acidic protein which exhibits an unusual fluorescence emission spectrum, characterized by a high contribution of tyrosine residues. Thioredoxin from A. nidulans cannot serve as a substrate for Escherichia coli thioredoxin reductase. Corn NADP-malate dehydrogenase is activated by this thioredoxin in the presence of dithiothreitol, while fructose-1,6-bisphosphatase is not. The amino acid sequence of Aspergillus thioredoxin was determined by automated Edman degradation after cleavage with trypsin, SV8 protease, chymotrypsin and cyanogen bromide. The masses of tryptic peptides were verified by plasma-desorption mass spectrometry. The mass of the protein was determined by electrospray mass spectrometry and shown to be in agreement with the calculated mass derived from the sequence (M(r) = 11,564). Compared to thioredoxins from other sources, the protein from A. nidulans displays a maximal sequence similarity with that from yeast (45%).
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PMID:Purification, properties and primary structure of thioredoxin from Aspergillus nidulans. 145 27

Thioredoxin, reduced either enzymatically with NADPH and NADP-thioredoxin reductase or chemically with dithiothreitol, reduced alpha-amylase and trypsin inhibitor proteins from several sources. Included were cystine-rich seed representatives from wheat (alpha-amylase inhibitors), soybean (Bowman-Birk trypsin inhibitor), and corn (kernel trypsin inhibitor). This system also reduced other trypsin inhibitors: the soybean Kunitz inhibitor, bovine lung aprotinin, and egg white ovoinhibitor and ovomucoid proteins. The ability of these proteins to undergo reduction by thioredoxin was determined by 1) a coupled enzyme activation assay with chloroplast NADP-malate dehydrogenase or fructose-1,6-bisphosphatase, 2) a dye reduction assay with 5',5'-dithiobis(2-nitrobenzoic acid), and 3) a direct reduction method based on the fluorescent probe, monobromobimane, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Reduction experiments with the seed proteins were carried out with thioredoxin from wheat germ (h-type) or Escherichia coli; the corresponding experiments with the animal trypsin inhibitors were carried out with thioredoxin from calf thymus or E. coli. In all cases, thioredoxin appeared to act catalytically; the reduced form of glutathione was without effect. When considered in conjunction with earlier results on purothionin (confirmed and extended in the current study), the new findings suggest that the NADP/thioredoxin system functions in the reduction of protein inhibitors of seeds and animal tissues. These results also raise the question of the occurrence of glutaredoxin in plants, as E. coli glutaredoxin was found to promote the reduction of some but not all of the proteins tested.
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PMID:Role of the NADP/thioredoxin system in the reduction of alpha-amylase and trypsin inhibitor proteins. 187 51

Two thioredoxins (named Ch1 and Ch2 in reference to their elution pattern on an anion-exchange column) have been purified to homogeneity from the green alga, Chlamydomonas reinhardtii. In this paper, we described the properties and the sequence of the most abundant form, Ch2. Its activity in various enzymatic assays has been compared with those of Escherichia coli and spinach thioredoxins. C. reinhardtii thioredoxin Ch2 can serve as a substrate for E. coli thioredoxin reductase with a lower efficiency when compared to the homologous system. In the presence of dithiothreitol (DTT), the protein is able to catalyze the reduction of porcine insulin. Thioredoxin Ch2 is as efficient as its spinach counterpart in the DTT or light activation of corn NADP-malate dehydrogenase, but it only activates spinach fructose-1, 6-bisphosphatase at very high concentrations. The complete primary structure of the C. reinhardtii thioredoxin Ch2 was determined by automated Edman degradation of the intact protein and of peptides derived from trypsin, chymotrypsin, clostripain, and SV8 protease digestions. It consists of a polypeptide of 106 amino acids (MW 11,808) and contains the well-conserved active site sequence Trp-Cys-Gly-Pro-Cys. The sequence of the algal thioredoxin Ch2 has been compared to that of thioredoxins from other sources and has the greatest similarity (67%) with the thioredoxin from Anabaena 7119.
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PMID:Purification, characterization, and complete amino acid sequence of a thioredoxin from a green alga, Chlamydomonas reinhardtii. 219 28

Oxidized thioredoxin undergoes sulfitolysis of its single disulfide bond at low concentrations of sulfite ions and protein and in the absence of denaturing agents. The reaction, which has an optimum at pH 8, was studied using [35S]sulfite and E. coli thioredoxin as model. The product, thioredoxin-S-sulfonate, has a half-life of several hours in solution. It is unable to activate chloroplast NADP malate dehydrogenase. Thioredoxin sulfitolysis may therefore be a physiologically important factor in mediating the phytotoxic effects of sulfur dioxide in plants.
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PMID:Inactivation of thioredoxin by sulfite ions. 220 Jul 7

A second thioredoxin, distinct from the one reported by Meng and Hogenkamp in 1981 (J. Biol. Chem. 256, 9174-9182), has been purified to homogeneity from an Escherichia coli strain containing a plasmid encoding a Corynebacterium nephridii thioredoxin. Thioredoxin genes from C. nephridii were cloned into the plasmid pUC13 and transformants were identified by complementation of a thioredoxin negative (trxA-) E. coli strain. The abilities of the transformants to support the growth of several phages suggested that more than one thioredoxin had been expressed [Lim et al. (1987) J. Biol. Chem. 262, 12114-12119]. In this paper we present the purification and characterization of one of these thioredoxins. The new thioredoxin from C. nephridii, designated thioredoxin C-2, is a heat-stable protein containing three cysteine residues/molecule. It serves as a substrate for C. nephridii thioredoxin reductase and E. coli and Lactobacillus leichmannii ribonucleotide reductases. Thioredoxin C-2 catalyzes the reduction of insulin disulfides by dithiothreitol or by NADPH and thioredoxin reductase and is a hydrogen donor for the methionine sulfoxide reductase of E. coli. Spinach malate dehydrogenase (NADP+) and phosphoribulokinase are activated by this thioredoxin while glyceraldehyde-3-phosphate dehydrogenase (NADP+) is not. Like the thioredoxin first isolated from C. nephridii, this new thioredoxin is not a reducing substrate for the C. nephridii ribonucleotide reductase. The complete primary sequence of this second thioredoxin has been determined. The amino acid sequence shows a high degree of similarity with other thioredoxins. Surprisingly, in contrast to the other sequences, this new thioredoxin contains the tetrapeptide -Cys-Ala-Pro-Cys- at the active site. With the exception of the T4 thioredoxin, this is the first example of a thioredoxin that does not have the sequence -Cys-Gly-Pro-Cys-. Our results suggest that, like plant cells, bacterial cells may utilize more than one thioredoxin.
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PMID:Purification, characterization and revised amino acid sequence of a second thioredoxin from Corynebacterium nephridii. 291 72

Thioredoxin is the best representative enzyme of a group of proteins, widely distributed and possessing dithiol-disulfide oxidoreductase activity. We have constructed a cDNA library from messenger RNAs isolated from a lymphoblastoid B cell line (Epstein-Barr virus-immortalized normal human lymphocytes). Screening of this library with synthetic oligonucleotide probes, constructed from the NH2-terminal amino acid sequence of a protein produced by this line, allowed us to identify a full-length cDNA clone coding for human thioredoxin. The open reading frame (315 nucleotides long) codes for a protein of 104 amino acids (excluding the initial methionine). This protein possesses the highly conserved enzymatic active site common to plant and bacterial thioredoxins: Trp-Cys-Gly-Pro-Cys (amino acids 30-34). These data provide for the first time the complete primary sequence of a thioredoxin of mammalian origin. Recombinant human thioredoxin, expressed in Escherichia coli, possesses a dithiol-reducing enzymatic activity as assayed on mammalian and plant substrates. It is able to reduce the interchain disulfide bridges of murine pentameric IgM and porcin insulin and also to activate vegetal NADP-malate dehydrogenase. Studies of human thioredoxin mRNA expression and regulation in immunocompetent cells of human origin indicate that the protein is weakly expressed in resting lymphocytes and monocytes, but the level of human thioredoxin mRNA transcription is quite important in activated monocytes and established dividing human cell lines.
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PMID:Cloning and expression of a cDNA for human thioredoxin. 317 May 95

Thioredoxin has been purified to homogeneity from the cyanobacterium Anabaena cylindrica. The protein consists of a single polypeptide chain with a relative molecular mass of about 11 680 which has two cysteine residues (residues 31 and 34) in the sequence-Cys-Gly-Pro-Cys- and an isoelectric point at pH 4.55. The N-terminal amino acid sequence of 39 residues shows distinct homologies with the sequences of Escherichia coli and Corynebacterium nephridii thioredoxins. Anti-(A. cylindrica thioredoxin) antiserum was used to quantify the thioredoxin which constituted about 0.22% of the soluble protein in cell-free extracts of N2-fixing, NO3- -grown or NH4+-grown A. cylindrica. Activation of fructose-1,6-bisphosphatase of A. cylindrica, activation of glutamine synthetase and NADP+-dependent malate dehydrogenase of the green alga Scenedesmus obliquus but not of A. cylindrica, and deactivation of glucose-6-P dehydrogenase of the cyanobacterium Anabaena variabilis were all achieved using the same thioredoxin species. No other thioredoxin species were detected in extracts of A. cylindrica when examined for the activation of these enzymes.
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PMID:Purification and characterization of thioredoxin from the N2-fixing cyanobacterium Anabaena cylindrica. 614 20

We have developed a method for the concomitant purification of several components of the ferredoxin/thioredoxin system of spinach chloroplasts. By applying this method to spinach-leaf extract or spinach-chloroplast extract we separated and purified three thioredoxins indigenous to chloroplasts. The three thioredoxins, when reduced, will activate certain chloroplast enzymes such as fructose-1,6-bisphosphatase and NADP-dependent malate dehydrogenase. Fructose-1,6-bisphosphatase is activated by thioredoxin f exclusively. Malate dehydrogenase is activated by thioredoxin mb and thioredoxin mc in a similar way, and it is also activated by thioredoxin f but with different kinetics. All three thioredoxins have very similar relative molecular masses of about 12,000 but distinct isoelectric points of 6.1 (thioredoxin f), 5.2 (thioredoxin mb) and 5.0 (thioredoxin mc). The amino acid composition as well as the C-terminal and N-terminal sequences have been determined for each thioredoxin. Thioredoxin f exhibits clear differences in amino acid composition and terminal sequences when compared with the m-type thioredoxins. Thioredoxin mb and thioredoxin mc, however, are very similar, the only difference being an additional lysine residue at the N-terminus of thioredoxin mb. Amino acid analyses, terminal sequences, immunological tests and the activation properties of the thioredoxins support our conclusion that thioredoxins mb and mc are N-terminal redundant isomers coming from one gene whereas thioredoxin f is a different protein coded by a different gene.
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PMID:Isomers in thioredoxins of spinach chloroplasts. 626 11

The present communication describes the properties of isocitrate dehydrogenase in crude extracts from the unicellular Anacystis nidulans and from heterocysts and vegetative cells of Nostoc muscorum and Anabaena cylindrica. The activity levels of this enzyme are much higher in heterocysts than in vegetative cells of N. muscorum and A. cylindrica. Isocitrate dehydrogenase is virtually inactive in vegetative cells of A. cylindrica. The enzyme is negatively regulated by the reduction charge and scarcely affected by oxoglutarate in the three cyanobacteria. The inhibition by ATP and ADP is competitive with respect to isocitrate and NADP+ in A. cylindrica and N. muscorum and noncompetitive in A. nidulans. Isocitrate dehydrogenase from the three cyanobacteria seems to be a hysteretic enzyme. All the experimental data suggest that the major physiological role of isocitrate and the isocitrate dehydrogenase in heterocysts is not to generate reducing equivalents for N2-fixation. Oxoglutarate formed by the enzyme reaction is likely required for the biosynthesis of glutamate inside the heterocysts. Thioredoxin preparations from spinach chloroplasts or from A. cylindrica activate isocitrate dehydrogenase from either heterocysts or vegetative cells of A. cylindrica. Activation is completed within seconds and requires dithiothreitol besides thioredoxin. The thioredoxin preparation which activates isocitrate dehydrogenase also activates NADP+-dependent malate dehydrogenase from spinach chloroplasts or heterocysts of A. cylindrica. Isocitrate dehydrogenase from A. cylindrica is deactivated by oxidized glutathione. It is speculated that isocitrate dehydrogenase and thioredoxin play a role in the differentiation of vegetative cells to heterocysts.
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PMID:The isocitrate dehydrogenase from cyanobacteria. 640 49


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