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PubMed1970

Effects of ischaemia on content of metabolites in rat liver and kidney in vivo.

1. The time-course of changes in content of intermediates of glycolysis in rat liver and kidney cortex after severance of blood supply was investigated. 2. The decline in content of ATP was more rapid in kidney (1.7-0.5mumol/g in 30s) than in liver (2.7-1.6mumol/g in 60s). In both tissues AMP and P(i) accumulated. 3. Net formation of lactate was 1.7mumol/g during the second minute of ischaemia in liver from well-fed rats, 1.1mumol/g in liver from 48h-starved rats, and about 1.0mumol/g during the first 30s of ischaemia in kidney. Net formation of alpha-glycerophosphate was rapid, especially in liver. 4. In kidney the concentration of beta-hydroxybutyrate rose, but that of alpha-oxoglutarate and acetoacetate decreased. 5. In both organs the concentrations of fructose diphosphate and triose phosphates increased during ischaemia and those of other phosphorylated C(3) intermediates decreased. 6. The concentration of the hexose 6-phosphates rose rapidly during the first minute of ischaemia in liver, but decreased during renal ischaemia. 7. In kidney the content of glutamine fell after 2min of ischaemia, and that of ammonia and glutamate rose. 8. The redox states of the cytoplasmic and mitochondrial NAD couple in kidney cortex were similar to those in liver. 9. The regulatory role of glycogen phosphorylase, pyruvate kinase and phosphofructokinase is discussed in relation to the observed changes in the concentrations of the glycolytic intermediates.

Acetoacetates↗
PubMed1972

The purification and properties of Escherichia coli methylglyoxal synthase.

1. Methylglyoxal synthase was purified over 1500-fold from glycerol-grown Escherichia coli K 12 strain CA 244. The purified enzyme was inactivated by heat or proteolysis, had a molecular weight of approx. 67000, a pH optimum of 7.5 and was specific for dihydroxyacetone phosphate with K(m) 0.47mm. 2. The possibility that a Schiff-base intermediate was involved in the reaction mechanism was investigated but not confirmed. 3. The purified enzyme lost activity, especially at low temperature, but could be stabilized by P(i). Two binding sites for P(i) may be present on the enzyme. Of other compounds tested only the substrate, dihydroxyacetone phosphate, and bovine serum albumin showed any significant stabilizing effect. 4. Phosphoenolpyruvate, 3-phosphoglycerate, PP(i) and P(i) were potent inhibitors of the enzyme. Kinetic experiments showed that PP(i) was apparently a simple competitive inhibitor, but inhibition by the other compounds was more complex. In the presence of P(i) the enzyme behaved co-operatively, with at least three binding sites for dihydroxyacetone phosphate. 5. It is proposed that methylglyoxal synthase and glyceraldehyde 3-phosphate dehydrogenase play important roles in the catabolism of the triose phosphates in E. coli. Channelling of dihydroxyacetone phosphate via methylglyoxal would not be linked to ATP formation and could be involved in the uncoupling of catabolism and anabolism.

Acetone↗
PubMed1974

Regulation of 'malic' enzyme of Solanum tuberosum by metabolites.

A purification of ;malic' enzyme from potato is described. The purified enzyme is specific for NADP and requires a bivalent cation for activity. At pH values below 7 the plot of rate versus malate concentration approximates to normal Michaelis-Menten kinetics. At pH values above 7 the plot of rate versus malate concentration is sigmoid. A number of dicarboxylic acids activate the enzyme and remove the sigmoidicity. The enzyme is inhibited by phosphate, triose phosphates and AMP. In general, effectors of the oxidative decarboxylation of malate behave in the same manner in the reductive carboxylation of pyruvate. The response of the enzyme to energy charge is reported and the physiological significance of the response to metabolites is discussed in relation to the proposed role of the enzyme in the control of pH.

Adenosine Diphosphate↗
PubMed1974

Studies on the subunit structure and amino acid sequence of trisoe phosphate isomerase from chicken breast muscle.

1. Triose phosphate isomerase was prepared by chromatography on DEAE-cellulose of an (NH(4))(2)SO(4) fraction of an extract of homogenized chicken breast muscle. The product is homogeneous on gel electrophoresis and is suitable for growing crystals for X-ray work. The specific activity is 10000 units/mg and the value for E(0.1%) (280) is 1.20. 2. Comparison between the sum of the amino acid compositions of the tryptic peptides of the protein and the amino acid composition obtained on total hydrolysis of the protein indicates that the relative subunit mass is about 27000. 3. These data, together with the results of the examination of the amino acid compositions of a number of minor peptides, the number of peptides in the tryptic digest and the complete amino acid sequences of the tryptic peptides (the determination of which is described here), give no indication that the subunits are dissimilar. 4. A tentative amino acid sequence is presented for the protein, in which the ordering of the tryptic peptides is derived by homology with the sequence of the rabbit muscle enzyme (Corran & Waley, 1973). 5. An appendix describes the use that was made of mass spectrometry in the determination of some of the sequences. Mass-spectrometric data have been obtained for 35 residues, that is about 15% of the total sequence of the protein. 6. An extended version of the present paper has been deposited as Supplementary Publication SUP 50025 at the British Library, Lending Division (formerly the National Lending Library for Science and Technology), Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies may be obtained on the terms given in Biochem. J. (1973) 131, 5.

Amino Acid Sequence↗
PubMed1974

Phosphonomethyl analogues of phosphate ester glycolytic intermediates.

Analogues of dihydroxyacetone phosphate and of 3-phosphoglycerate were made in which the phosphate group, -O-PO(3)H(2), is replaced by the phosphonomethyl group, -CH(2)-PO(3)H(2). The analogue of dihydroxyacetone phosphate is a substrate for aldolase and glycerol 1-phosphate dehydrogenase (Stribling, 1974), but not for triose phosphate isomerase. The analogue of 3-phosphoglycerate oxidizes NADH under the combined action of 3-phosphoglycerate kinase and glyceraldehyde 3-phosphate dehydrogenase if ATP is added. Thus four out of the five glycolytic enzymes tested handle the phosphonomethyl compounds like the natural phosphates.

Adenosine Triphosphate↗
PubMed1976

Inhibition of glycolytic enzymes by 2-phosphotartronate.

2-Phosphotartronate has been synthesized by permanganate oxidation of glycerol 2-phosphate and has been tested as an inhibitor of five glycolytic enzymes that bind phosphoglycerate or phosphoglycollate. Competitive inhibition of rabbit muscle phosphoglycerate mutase, enolase and pyruvate kinase was observed. Triose phosphate isomerase and 3-phosphoglycerate kinase were not inhibited.

Animals↗
PubMed1986

Metabolic effects of D-glyceraldehyde in isolated hepatocytes.

The effects of D-glyceraldehyde on the hepatocyte contents of various metabolites were examined and compared with the effects of fructose, glycerol and dihydroxyacetone, which all enter the glycolytic/gluconeogenic pathways at the triose phosphate level. D-Glyceraldehyde (10 MM) caused a substantial depletion of hepatocyte ATP, as did equimolar concentrations of fructose and glycerol. D-Glyceraldehyde and fructose each caused a 2-fold increase in fructose 1,6-bisphosphate and the accumulation of millimolar quantities of fructose 1-phosphate in the cells. D-Glyceraldehyde caused an increase in the glycerol 3-phosphate content and a decrease in the dihydroxyacetone phosphate content, whereas dihydroxyacetone increased the content of both metabolites. The increase in the [glycerol 3-phosphate]/[dihydroxyacetone phosphate] ratio caused by D-glyceraldehyde was not accompanied by a change in the cytoplasmic [NAD+]/[NADH] ratio, as indicated by the unchanged [lactate]/[pyruvate] ratio. The accumulation of fructose 1-phosphate from D-glyceraldehyde and dihydroxyacetone phosphate in the hepatocyte can account for the depletion of the intracellular content of the latter. Presumably ATP is depleted as the result of the accumulation of millimolar amounts of a phosphorylated intermediate, as is the case with fructose and glycerol. It is suggested that the accumulation of fructose 1-phosphate during hepatic fructose metabolism is the result of a temporary increase in the D-glyceraldehyde concentration because of the high rate of fructose phosphorylation compared with triokinase activity. The equilibrium constant of aldolase favours the formation and thus the accumulation of fructose 1-phosphate.

Adenosine Triphosphate↗
PubMed2001

Structural determinants for ligand binding and catalysis of triosephosphate isomerase.

The crystal structure of leishmania triosephosphate isomerase (TIM) complexed with 2-(N-formyl-N-hydroxy)-aminoethyl phosphonate (IPP) highlights the importance of Asn11 for binding and catalysis. IPP is an analogue of the substrate D-glyceraldehyde-3-phosphate, and it is observed to bind with its aldehyde oxygen in an oxyanion hole formed by ND2 of Asn11 and NE2 of His95. Comparison of the mode of binding of IPP and the transition state analogue phosphoglycolohydroxamate (PGH) suggests that the Glu167 side chain, as well as the triose part of the substrate, adopt different conformations as the catalysed reaction proceeds. Comparison of the TIM-IPP and the TIM-PGH structures with other liganded and unliganded structures also highlights the conformational flexibility of the ligand and the active site, as well as the conserved mode of ligand binding.

Aminoethylphosphonic Acid↗
PubMed1997

Analysis of the immune response elicited by a multiple antigen peptide (MAP) composed of two distinct protective antigens derived from the parasite Schistosoma mansoni.

In this report we analyse the immune response elicited by a Multiple Antigen Peptide (MAP), containing three peptide sequences derived from two distinct vaccine candidates against schistosomiasis; the Schistosoma mansoni 28 kDa Gluthatione-S-Transferase (Sm28GST) and the Schistosoma mansoni Triose-Phosphate-Isomerase (sTPI). We examined the immunogenicity of this construct, named MAP 'DA', in three distinct mouse strains. The B-cell response, studied by measuring the production of different IgG isotypes, was mainly directed against the peptide derived from the Sm28GST, but also against the whole Sm28GST protein. In contrast, the T-cell response, as assessed by proliferation assay and cytokine mRNA expression, was directed against the MAP construct, the peptides derived from the sTPI protein and the whole sTPI protein. Significantly, T-cells from all MAP 'DA'-immunized mice, restimulated in vitro was the sTPI antigen, expressed IFN-gamma specific messengers. This cytokine has been described to play a major role in the reduction of the Schistosoma mansoni pathology. We thus demonstrate that a single MAP construct, composed of peptides from distinct antigens of Schistosoma mansoni, induced a B- and T-cell response, including production of potentially protective IFN-gamma, irrespective of the MHC background.

Animals↗
PubMedDate not supplied

Blood preservation. XXXIV. DHA maintains 2,3-DPG and its adverse effect on ATP is reversed with extra phosphate.

We have found that the addition of 10 mM inorganic phosphate to DHA in CPD-adenine maintains ATP levels at normal or higher than normal values for six weeks of storage. 2,3-DPG values are slightly lowered by the extra phosphate, but are still maintained at approximately half normal for four weeks by the DHA. The addition of a higher phosphate concentration, 20 mM, to DHA produced lower levels of ATP and 2,3-DPG than those observed with 10 mM phosphate, although both levels were better than in the CPD-adenine control. pH values in this experiment were lowest in the three preservatives containing DHA, probably indicating increased lactate production due to metabolism of this triose sugar, in addition to dextrose present in CPD.

Adenine↗
PubMed1990

Searching sequence space by definably random mutagenesis: improving the catalytic potency of an enzyme.

How easy is it to improve the catalytic power of an enzyme? To address this question, the gene encoding a sluggish mutant triose-phosphate isomerase (D-glyceraldehyde-3-phosphate ketol-isomerase, EC 5.3.1.1) has been subjected to random mutagenesis over its whole length by using "spiked" oligonucleotide primers. Transformation of an isomerase-minus strain of Escherichia coli was followed by selection of those colonies harboring an enzyme of higher catalytic potency. Six amino acid changes in the Glu-165----Asp mutant of triosephosphate isomerase improve the specific catalytic activity of this enzyme (from 1.3-fold to 19-fold). The suppressor sites are scattered across the sequence (at positions 10, 96, 97, 167, and 233), but each of them is very close to the active site. These experiments show both that there are relatively few single amino acid changes that increase the catalytic potency of this enzyme and that all of these improvements derive from alterations that are in, or very close to, the active site.

Aspartic Acid↗
PubMed1996

Inhibition of Plasmodium falciparum malaria using antisense oligodeoxynucleotides.

We studied inhibition of growth of the malaria parasite Plasmodium falciparum in in vitro culture using antisense (AS) oligodeoxynucleotides (ODNs) against different target genes. W2 and W2mef strains of drug-resistant parasites were exposed to AS ODNs over 48 hr, and growth was determined by microscopic examination and [3H]hypoxanthine incorporation. At ODN concentrations of 1 microM, phosphorothioate (PS) ODNs inhibited growth in a target-independent manner. However, between 0.5 and 0.005 microM, ODNs against dihydrofolate reductase, dihydropteroate synthetase, ribonucleotide reductase, the schizont multigene family, and erythrocyte binding antigen EBA175 significantly inhibited growth compared with a PS AS ODN against human immunodeficiency virus, two AS ODNs containing eight mismatches, or the sense strand controls (P < 0.0001). The IC50 was approximately 0.05 microM, whereas that for non-sequence-specific controls was 15-fold higher. PS AS ODNs against DNA polymerase alpha showed less activity than that for other targets, whereas a single AS ODN against triose-phosphate isomerase did not differ significantly from controls. We conclude that at concentrations below 0.5 microM, PS AS ODNs targeted against several malarial genes significantly inhibit growth of drug-resistant parasites in a nucleotide sequence-dependent manner. This technology represents an alternative method for identifying malarial genes as potential drug targets.

Animals↗
PubMed2005

Genetic perturbation of glycolysis results in inhibition of de novo inositol biosynthesis.

In a genetic screen for Saccharomyces cerevisiae mutants hypersensitive to the inositol-depleting drugs lithium and valproate, a loss of function allele of TPI1 was identified. The TPI1 gene encodes triose phosphate isomerase, which catalyzes the interconversion of dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate. A single mutation (N65K) in tpi1 completely abolished Tpi1p enzyme activity and led to a 30-fold increase in the intracellular DHAP concentration. The tpi1 mutant was unable to grow in the absence of inositol and exhibited the "inositol-less death" phenotype. Similarly, the pgk1 mutant, which accumulates DHAP as a result of defective conversion of 3-phosphoglyceroyl phosphate to 3-phosphoglycerate, exhibited inositol auxotrophy. DHAP as well as glyceraldehyde 3-phosphate and oxaloacetate inhibited activity of both yeast and human myo-inositol-3 phosphate synthase, the rate-limiting enzyme in de novo inositol biosynthesis. Implications for the pathology associated with TPI deficiency and responsiveness to inositol-depleting anti-bipolar drugs are discussed. This study is the first to establish a connection between perturbation of glycolysis and inhibition of de novo inositol biosynthesis.

Amino Acid Sequence↗
PubMed1981

A simple procedure for the isolation of seven abundant muscle enzymes.

The present work describes procedures in which seven major muscle enzymes and serum albumin can be simultaneously isolated from chicken skeletal muscles. The seven enzymes isolated were: phosphorylase, enolase, creatine-P kinase, aldolase, glyceraldehyde-3-P dehydrogenase, phosphoglycerate mutase, and triose-P isomerase. The proteins isolated by these methods were judged to be greater than 97% pure on the basis of electrophoretic analysis in sodium dodecyl sulfate polyacrylamide gels. The procedure is applicable for isolation of the enzymes from large (greater than 100 g) or small (less than 0.5 g) amounts of muscle tissue and the entire procedure can be completed within two days. Particularly useful features of the procedures are: (1) preferential solubilization of the enzymes from myofibrils by extraction of muscle specimens in solutions of different ionic strength; (2) specific precipitation of phosphorylase, creatine-P kinase, and glyceraldehyde 3-Phosphate dehydrogenase from solutions of specified pH and degrees of ammonium sulfate saturation; and (3) an alternate method for isolation of glyceraldehyde-3-P dehydrogenase by specific elution of the enzyme from phosphocellulose columns with ATP. Because of the ease, rapidity, and reproducibility of the procedures, these methods may be useful for the routine isolation of the muscle enzymes in studies on biochemical regulation, as well as for obtaining large quantitites of the enzymes for structural analysis.

Animals↗
PubMed1987

High performance purification of glycolytic enzymes and creatine kinase from chicken breast muscle and preparation of their specific immunological probes.

We developed a novel procedure for isolation of the muscle isozymes of aldolase, triose phosphate isomerase (TPI), glyceraldehyde phosphate dehydrogenase (GAPDH), phosphoglycerate kinase (PGK), phosphoglycerate mutase (PGM), enolase, pyruvate kinase (PK) and lactic dehydrogenase (LDH), and also creatine kinase (CK), at high purity, specific activity and yield. Protein was extracted from chicken breast muscle and glycolytic enzymes were purified by a three step procedure consisting of: Ammonium sulfate combined with pH fractionation. Phosphocellulose chromatography with performance of high pressure liquid chromatography, exploiting a pH gradient formed by a gradient of the buffering ion for protein elution. Affinity chromatography causing elution by substrate or pH. The enzymes, obtained at over 95% purity as judged by specific activity and silver stained electropherograms, were injected into sheep. Antibody for each enzyme was purified on specific immunosorbant and its specificity was verified by immunotransfer analysis.

Animals↗
PubMed2006

Incorporating allelic variation for reconstructing the evolutionary history of organisms from multiple genes: An example from Rosa in North America.

Allelic variation within individuals holds information regarding the relationships of organisms, which is expected to be particularly important for reconstructing the evolutionary history of closely related taxa. However, little effort has been committed to incorporate such information for reconstructing the phylogeny of organisms. Haplotype trees represent a solution when one nonrecombinant marker is considered, but there is no satisfying method when multiple genes are to be combined. In this paper, we propose an algorithm that converts a distance matrix of alleles to a distance matrix among organisms. This algorithm allows the incorporation of allelic variation for reconstructing the phylogeny of organisms from one or more genes. The method is applied to reconstruct the phylogeny of the seven native diploid species of Rosa sect. Cinnamomeae in North America. The glyceralgehyde 3-phosphate dehydrogenase (GAPDH), the triose phosphate isomerase (TPI), and the malate synthase (MS) genes were sequenced for 40 individuals from these species. The three genes had little genetic variation, and most species showed incomplete lineage sorting, suggesting these species have a recent origin. Despite these difficulties, the networks (NeighborNet) of organisms reconstructed from the matrix obtained with the algorithm recovered groups that more closely match taxonomic boundaries than did the haplotype trees. The combined network of individuals shows that species west of the Rocky Mountains, Rosa gymnocarpa and R. pisocarpa, form exclusive groups and that together they are distinct from eastern species. In the east, three groups were found to be exclusive: R. nitida-R. palustris, R. foliolosa, and R. blanda-R. woodsii. These groups are congruent with the morphology and the ecology of species. The method is also useful for representing hybrid individuals when the relationships are reconstructed using a phylogenetic network.

Algorithms↗
PubMed1988

FUS: a system to simulate conformational changes in biological macromolecules.

In order to study the dynamics of protein and nucleic acid conformations, a molecular folding-unfolding system (FUS written in Lisp) has been developed. Secondary structure features of protein and nucleic acids are graphically represented by cubes in a modified 'Blocks World' paradigm. Modeling of protein and nucleic acid unfolding (denaturation) and folding of their three-dimensional structure is possible by the use of high level 'block' operators which allow displacement of these structural features in space. Due to the flexible nature of this program, FUS is a useful tool for the rapid evaluation of user-defined rules governing conformational changes. The use of FUS to unfold three common proteins (prealbumin, flavodoxin and triose phosphate isomerase) and a tRNA is presented.

Computer Simulation↗
PubMed1991

Identification and applications of repetitive probes for gene mapping in the mouse.

Interspecific mouse hybrids that are viable and fertile provide a wealth of genetic variation that is useful for gene mapping. We are using this genetic variation to develop multilocus linkage maps of the mouse genome. As an outgrowth of this work, we have identified three repetitive probes that collectively identify 28 loci dispersed on 16 of the 19 mouse autosomes and the X chromosome. These loci establish a skeleton linkage map that can be used to detect linkage over much of the mouse genome. The molecular probes are derived from the mouse mammary tumor virus envelope gene, the ornithine decarboxylase gene, and the triose phosphate isomerase gene. The ability to scan the mouse genome quickly and efficiently in an interspecific cross using these three repetitive probes makes this system a powerful tool for identifying the chromosomal location of mutations that have yet to be cloned, mapping multigenic traits, and identifying recessive protooncogene loci associated with murine neoplastic disease. Ultimately, interspecific hybrids in conjunction with repetitive and single-copy probes will provide a rapid means to access virtually any gene of interest in the mouse genome at the molecular level.

Animals↗