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

---

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.
...
PMID:Non-redox protein interactions in the thioredoxin activation of chloroplast enzymes. 132 Sep 37

The chloroplastic enzyme NADP-malate dehydrogenase is activated by a reversible thiol/disulfide interchange with reduced thioredoxin. Its target disulfide bridge is considered to be located at the amino terminus. To further substantiate the regulatory role of this disulfide, site-directed mutagenesis has been used to replace each or both of the amino-terminal cysteines of the sorghum leaf NADP-malate dehydrogenase, expressed in Escherichia coli, by serines. A truncation mutant lacking the amino terminus has also been produced. Surprisingly, the mutant proteins still required activation by reduced thioredoxin. However, their activation was almost instantaneous, whereas the native enzyme reached full activity after a 10-20 min preincubation. The 8 1/2 for reduced thioredoxin was decreased 2-fold in the mutants, but their Km values for NADPH and oxaloacetate did not change significantly. The inhibition of activation by NADP and inhibition of activity by thiol-derivatizing agents were also retained. These results are interpreted as an indication that two thioredoxin-dependent reduction steps are involved in NADP-dependent malate dehydrogenase light activation, hence that two disulfides per monomer participate in the process. The overall activation rate would depend on a conformational change following the reduction of the amino-terminal disulfide bridge. The amino terminus also plays a role in the dimerization of the protein.
...
PMID:Site-directed mutagenesis reveals the involvement of an additional thioredoxin-dependent regulatory site in the activation of recombinant sorghum leaf NADP-malate dehydrogenase. 140 Apr 68

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%).
...
PMID:Purification, properties and primary structure of thioredoxin from Aspergillus nidulans. 145 27

Thioredoxins are low molecular weight proteins which serve as hydrogen donors in a wide variety of redox reactions via reversible formation of a disulfide bridge between two neighboring cysteins. We present data demonstrating that in Dictyostelium discoideum thioredoxins constitute a highly conserved multigene family. We have isolated cDNA clones coding for three different Dictyostelium thioredoxins which show 80% mutual identity. Analysis of genomic Southern blots suggests the presence of additional genes. Except for the active site (Trp-Cys-Gly-Pro-Cys), there are only a few amino acid identities with thioredoxins from other organisms. Identity scores do not exceed 43%, the value found with the human lymphocyte protein. DdTRX1 was expressed in Escherichia coli, purified, and shown to have thioredoxin activity, as judged by its capacity to activate the NADP-malate dehydrogenase. Due to its life cycle, during which individual amoebae form a multicellular fruiting body, Dictyostelium is used to study developmental processes such as cell-type differentiation and regulation of gene expression. Transcript levels of Dictyostelium thioredoxins were regulated during the developmental cycle. Low levels of mRNAs could be detected during growth. After the onset of development, where essentially no cell divisions take place, message levels increased with maximal expression during aggregation. In later multicellular stages, RNA levels declined again. The same expression pattern could be seen for all cloned thioredoxins. Protein levels paralleled this time course with a delay of several hours as judged by Western blot and activity measurements.
...
PMID:Thioredoxins from Dictyostelium discoideum are a developmentally regulated multigene family. 157 20

A new over-expression system has been set up for Escherichia coli thioredoxin, yielding 55 mg purified protein/10 g fresh cells. This system has been used to produce thioredoxin modified by site-directed mutagenesis. Taking advantage of the structural and enzymatic similarity between E. coli and spinach m-type thioredoxin, Asp61 of E. coli thioredoxin has been changed into Asn in order to investigate the impact of the suppression of a charged residue on the interaction of thioredoxin with target enzymes. The modification did not significantly alter the structure of the protein. Neither the rate of reduction of insulin and 5,5'-dithio-bis(2-nitrobenzoic acid) by the reduced thioredoxin, nor the reduction by NADPH-dependent thioredoxin reductase, have been modified. The major effect of the mutation was observed for chloroplast enzyme activation with thioredoxin reduced by dithiothreitol and with thioredoxin reduced by ferredoxin-dependent thioredoxin reductase in a light-activation reconstituted chloroplast system. The substitution of the negatively charged Asp61 by the neutral Asn led to an increase in the efficiency of spinach fructose-1,6-bisphosphatase activation by the dithiothreitol-reduced thioredoxin, and to an increase in both spinach fructose-1,6-bisphosphatase and corn NADP-dependent malate dehydrogenase activities in the light-activation system. This suggests that the suppression of the negative charge improves the reactivity of thioredoxin with chloroplast enzymes such as fructose-1,6-bisphosphatase and ferredoxin-dependent thioredoxin reductase.
...
PMID:Mutation of a negatively charged amino acid in thioredoxin modifies its reactivity with chloroplastic enzymes. 184 15

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.
...
PMID:Role of the NADP/thioredoxin system in the reduction of alpha-amylase and trypsin inhibitor proteins. 187 51

Ferredoxin-thioredoxin reductase (FTR) is an iron-sulfur protein which, in the presence of ferredoxin and thioredoxin, catalyses the activation of photosynthetic enzymes such as fructose-1,6-bisphosphatase, NADP-malate dehydrogenase and several others. The results from amino acid composition and N- and C-terminal sequences show that spinach FTR is composed of two nonidentical subunits (mol.wt. = 17,200: A; 15,500:B) present in equal amounts. Other components (mol. wt. = 16,300 and 14,200) observed in preparations are most likely derived from subunit A losing its amino terminal part. We report the amino acid compositions of the two subunits A and B of FTR including their partial terminal sequences. Subunit A has an additional amino-terminal serine-rich sequence which is phosphorylated.
...
PMID:Characterization of spinach ferredoxin-thioredoxin reductase. 192 73

A second thioredoxin, Ch1, distinct from the one recently reported [Decottignies, P., Schmitter, J.M., Jacquot, J. P., Dutka, S., Picaud, A. & Gadal, P. (1990) Arch, Biochem. Biophys. 280, 112-121] has been purified from the green alga, Chlamydomonas reinhardtii, and its functional and structural properties investigated. Its activity in various enzymatic assays has been compared with the activities of different plant thioredoxins (Ch2 from C. reinhardtii and spinach m and f). Ch1 cannot serve as a substrate for Escherichia coli thioredoxin reductase, but can be reduced by spinach ferredoxin-thioredoxin reductase. It is less efficient than its spinach counterpart in the activation of corn leaf NADP-dependent malate dehydrogenase by light or dithiothreitol, and it only activates spinach fructose-1,6-bisphosphatase at very high concentrations. The complete primary structure of C. reinhardtii thioredoxin Ch1 was determined by automated Edman degradation of the intact protein and of peptides derived from trypsin, chymotrypsin and Staphylococcus aureus V8 protease digestions. When needed, peptide masses were verified by plasma desorption mass spectrometry. Ch1 consists of a polypeptide of 111 amino acids (11634 Da) and contains the well-conserved active site sequence Trp-Cys-Gly-Pro-Cys. Compared to thioredoxins from other sources, the algal thioredoxin Ch1 displays few sequence similarities with all the thioredoxins sequenced so far. Preliminary evidence indicates that Ch1 may be an h-type thioredoxin.
...
PMID:Characterization and primary structure of a second thioredoxin from the green alga, Chlamydomonas reinhardtii. 204 Mar 9

The reactivity of human thioredoxin (HTR) was tested in several reactions. HTR was as efficient as E. coli or plant and algal thioredoxins when assayed with E. coli ribonucleotide reductase or for the reduction of insulin. On the other hand, HTR was poorly reduced by NADPH and the E. coli flavoenzyme NADPH thioredoxin reductase as monitored in the DTNB reduction test. When reduced with dithiothreitol (DTT), HTR was much less efficient than thioredoxin m and thioredoxin f, the respective specific thioredoxins for the chloroplast enzymes NADP-malate dehydrogenase (NADP-MDH) and fructose 1,6 bisphosphatase (FBPase). Finally, HTR could be used in the photoactivation of NADP-MDH although less efficiently than thioredoxin m, proving nevertheless that it can be reduced by the iron sulfur enzyme ferredoxin thioredoxin reductase in the presence of photoreduced ferredoxin. Based on sequence comparisons, it was expected that HTR would display a reactivity similar to chloroplast thioredoxin f rather than to thioredoxin m. However the observed behavior of FTR did not exactly fit this prediction. The results are discussed in relation to the structural data available for the proteins.
...
PMID:Human thioredoxin reactivity-structure/function relationship. 217 90

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.
...
PMID:Purification, characterization, and complete amino acid sequence of a thioredoxin from a green alga, Chlamydomonas reinhardtii. 219 28


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

---