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At least 613 records · Page 34Linked to original sources
PubMed1969

Lactate dehydrogenase isozymes in human cardiac transplantation.

Lactate dehydrogenase (LDH) isozyme activities have been followed in 17 human cardiac allografts. A pattern of abnormality associated with cardiac rejection during the first month after operation has been determined: (i) LDH-1 activity is greater than LDH-2 activity; (ii) LDH-1 activity is greater than 35 percent of total LDH activity; and (iii) LDH-1 activity is greater than 100 international units. The LDH-1 abnormality helps to meet the need for an index of cardiac rejection during the early weeks after operation when the electro-cardiogram is least reliable.

Heart Transplantation↗
PubMed1990

Limited proteolysis of bovine muscle and heart lactate dehydrogenase is inhibited by phospholipid liposome interaction.

Limited proteolysis of phospholipid complexes of heart and muscle bovine lactate dehydrogenase by trypsin and chymotrypsin has been studied under nondenaturing condition at pH 7.5. Chymotrypsin cleaves the polypeptide chain of heart and muscle lactate dehydrogenase into two principal fragments and LDH subunits were protected by lipids towards the proteinase attack. Enzymatic activity of heart and muscle lactate dehydrogenase was abolished by limited proteolytic cleavage. In complexes, both isoenzymes were protected against proteinases attack by lipids.

Animals↗
PubMed1986

Lactate dehydrogenase isoenzyme changes during facial development.

Lactate dehydrogenase activity (LDH) was demonstrated by a histochemical technique in free, dissected, facial processes of rats from the ninth embryonic day. Facial processes of embryonic rats aged 9-15 days were analysed by isoelectric focusing for their isoenzymic distribution of LDH. A dominance of LDH-5, LDH-4 and LDH-3 isoenzymes was observed. As a comparison, LDH isoenzymes from mandibular and maxillary processes of rat embryos aged 9-11 days revealed only LDH-5 and, to a smaller extent, LDH-4. These results constitute evidence for prominent anaerobic metabolism in these tissues during early facial development. Intense staining for LDH was seen in surface epithelium, respiratory epithelium and in myogenic and osteogenic areas.

Animals↗
PubMed1987

Inactivation of human lactate dehydrogenase isozymes by sulfhydryl reagents.

Human lactate dehydrogenase isozymes, LDH-1 and LDH-5, were inactivated at 25 degrees C and pH 7.5 by N-alkylmaleimides of varying chain length, and by fluorescein mercuric acetate. Second-order rate constants for the inactivation of LDH-5 by N-alkylmaleimides increased with increasing chain length of the maleimide derivative while essentially no chain-length effect was observed in the inactivation of LDH-1. Both isozymes were effectively inactivated by low concentrations of fluorescein mercuric acetate, and in both cases saturation kinetics were observed. Dissociation constants obtained from double-reciprocal plotting methods indicated a twofold better binding of fluorescein mercuric acetate to LDH-1. Protection from fluorescein mercuric acetate by NAD was observed with both enzymes.

Fluoresceins↗
PubMed1975

Amino- and carboxyl-terminal analyses of hepatoma lactate dehydrogenase isozymes.

The M4 isozyme of lactate dehydrogenase was purified to homogeneity from normal rat liver and from two Morris hepatomas (7777 and 7793). Amino-terminal analyses with fluorodinitrobenzene failed to detect the presence of free amino-terminal residues in each enzyme studied. Each enzyme contained between 3.7 and 4.1 moles of protein-bound acetyl groups per mole of enzyme. The amino-terminal peptide, characterized as N-acetylalanylalanine, was isolated from Pronase digests of each isozyme preparation, and quantitative recovery experiments indicated that all acetyl residues were bound at the amino termini. Carboxylterminal analyses demonstrated phenylalanine to be the carboxyl-terminal residue in each enzyme studied. These data indicate no differences in either amino- or carboxyl-terminal regions of the hepatoma M4 isozymes compared to normal liver M4 isozyme.

Alanine↗
PubMed1989

Crystallization of and preliminary crystallographic data for allosteric L-lactate dehydrogenase from Bifidobacterium longum.

L-Lactate dehydrogenase from Bifidobacterium longum aM101-2 was overexpressed in Escherichia coli and then purified. The enzyme was crystallized from a polyethylene glycol 6000 solution by the hanging drop vapor diffusion method. Crystals grown in the presence of NADH (type II), both NADH and oxamate (type III), and NADH, oxamate, and FBP (type IV) were analyzed. All three crystal forms belong to the orthorhombic system, space group P2(1)2(1)2. The cell dimensions of the type II crystals were a = 106.2 A, b = 131.6 A, and c = 63.8 A. Those of the type III and type IV crystals were a = 106.4 A, b = 131.4 A, and c = 63.8 A. The type III crystals diffract X-rays to beyond 2.5 A spacing. The type II and type III crystals were stable as to X-ray irradiation.

Allosteric Site↗
PubMed1970

Purificationa and properties of a fructose-1,6-diphosphate-activated lactate dehydrogenase from Streptococcus faecalis.

An l-(+)-lactate dehydrogenase was purified approximately 35-fold from crude extracts of Streptococcus faecalis. The purified enzyme had an absolute and specific requirement for fructose-1,6-diphosphate (FDP) for catalytic activity. The concentration of FDP required for 50% maximal activity was about 0.045 mm. The activator was bound to the enzyme more effectively at pH 5.8 than it was at a neutral or alkaline pH. Activation appeared to involve a conformational change in the enzyme which made the substrate and coenzyme sites more accessible to the respective reactants. Among the evidence supporting this hypothesis was the fact that FDP lowered significantly the apparent K(m) for both pyruvate and reduced nicotinamide adenine dinucleotide. Moreover, the enzyme, which was quite heat stable in the absence of any of the reactants, was rendered heat labile by FDP.

Bacterial Proteins↗
PubMed1997

Minimal functional unit of lactate dehydrogenase.

The tetrameric heart isozyme of lactate dehydrogenase (H4) is modified by p-chloromercuribenzoate (PCMB) to produce the inactive tetramer (H4) and then hybridized with native tetrameric muscle isozyme (M4). The hybrid mixture (M4, H'M3, H2'M2, H3'M, and H4') was isolated by polyacrylamide gel electrophoresis (PAGE) and then stained for enzyme activity and with Coomassie brilliant blue. Only three bands were found on the gels in either case. The hybrid enzymes (H'M3 and H2'M2) as isolated by PAGE have half the specific activity of the native muscle enzyme. The electrophoresis properties of H'M3 are very similar to those of HM3, while the electrophoresis properties of H2'M2 are very similar to those of H2M2. The above results strongly suggest that the tetramer having enzymatic activity contains at least two native subunits, and the di-subunit in the tetrameric enzyme is the minimal functional unit.

Animals↗
PubMed1999

Lactate dehydrogenase isoenzyme patterns in cetaceans.

Serum lactate dehydrogenase (LDH) isoenzyme activity was analyzed in cetaceans. Animals that were treated by i.m. injection and others that received azole therapy had distinctly different LDH isoenzyme profiles. A third distinctive pattern was occasionally observed in clinically normal animals with elevations in total transaminase and LDH activity levels. DH isoenzyme activity patterns were not affected by mild or moderate hemolysis, refrigeration after 24 hr, or freezing for 24 hr with subsequent thawing. However, severe hemolysis produced artifactual changes similar to those observed in individuals that received injections but of a lesser magnitude. DH isoenzyme activity patterns may provide useful corroboration of other clinical findings when diagnostic modalities are limited, especially to differentiate nonspecific enzyme elevation from nonpathologic elevations in serum enzyme concentrations due to i.m. injections or azole therapy.

Alanine Transaminase↗
PubMed1981

Purified reduced nicotinamide adenine dinucleotide: responses to lactate dehydrogenase isozymes from three cell sources.

Lactate dehydrogenase (LDH, E.C. 1.1.1.27) isozymes from three single-cell sources reacted differently with reduced nicotinamide adenine dinucleotide (NADH) purified to published chromatographic and spectrophotometric specifications and free of inhibitors of LDH, when compared with a commercial preparation of NADH. The activity of LDH-1, purified from rabbit erythrocytes, increased the most with inhibitor-free NADH; the next most stimulated were the LDH isozymes from a control hepatocyte line; but hardly responsive at all were the same isozymes from chemically transformed cells. Thus isozyme composition alone did not account for the range of responses to purified NADH. The commercial preparation of NADH used in these studies contains the Strandjörd-Clayson inhibitors, the most potent group identified in NADH preparations relative to LDH activity. The results suggest that specific molecular differences in individual isozymes contribute to the differential response to the Strandjörd-Clayson inhibitors.

Animals↗
PubMed1995

Evolutionary relations among vertebrate muscle-type lactate dehydrogenases.

Gene duplication has produced two lactate dehydrogenase (LDH) isozymes, LDH-A and LDH-B, that are found in essentially all vertebrates. On the basis of the biochemical properties of the LDH-A and LDH-B isozymes, it has been suggested that each locus is orthologous among all vertebrates. However, phylogenetic studies have not supported a common evolutionary history among the LDH-A isozymes, particularly when those from lower vertebrates are examined. We present here the sequence of a muscle-type LDH from Fundulus heteroclitus, a teleost fish for which the LDH-B sequence has been determined and shown to be unrelated phylogenetically to tetrapod LDH-A isozymes. Although the sequence of the teleost muscle LDH shares certain features with the LDH-A of tetrapods, phylogenetic analyses do not support an orthologous relation among the LDH-A isozymes of teleost fish and tetrapod vertebrates.

Amino Acid Sequence↗
PubMed2002

Improved partitioning in aqueous two-phase system of tyrosine-tagged recombinant lactate dehydrogenase.

The partitioning of Bacillus stearothermophilus lactate dehydrogenase (LDH) in an aqueous two-phase system was studied. Particularly, the influence of tyrosine tags on the partitioning was evaluated. The hydrophobic effect, caused by the addition of tyrosine residues, was determined in a system based on dextran and the thermoseparating ethylene oxide-propylene oxide random copolymer (EO30PO70). Five different LDH variants were constructed with N-terminal tags containing tyrosines (Y3 and Y6), tyrosines and prolines (Y3P2 and Y6P2), and only prolines (P2). LDH fused with tags containing tyrosines increased the partitioning coefficient, and the more tyrosines added to the protein, the larger improvement in partitioning. When prolines were added between the tyrosine-rich tag and the protein, a further increased partitioning was obtained. The enhanced partitioning was attributed to the rigid structure of the proline, which in turn led to an increase in the exposure of the tag to the surroundings. The best tyrosine tag, Y6P2, increased the partition coefficient four times and additionally, a higher thermostability was observed.

Amino Acid Sequence↗
PubMed1989

Laboratory and clinical features of lactate dehydrogenase subunit deficiencies.

Heterozygous subjects with lactate dehydrogenase (LD) subunit deficiencies do not always show a low serum LD activity. Thus, it is necessary to examine the serum and erythrocyte LD isozyme patterns when screening for these conditions. We assessed patients with heterozygotes for H and M subunit deficiency by immunoblotting with anti-H subunit antibody. We could not find any protein or variant proteins in the heterozygous subjects with M subunit deficiency. On the other hand, the existence of variant protein was confirmed in the heterozygous subjects with H subunit deficiency. However, in one patient with homozygous for H subunit deficiency, no H subunit protein was observed. It is suggested that possibly many types of LD subunit deficiency may exist. Only patients with homozygous for M subunit deficiency show common patterns of clinical findings. All patients with LD subunit deficiencies have the risk of misdiagnosis of other clinical conditions from laboratory data because LD release is reduced. Thus it is important to detect them as a latent hereditary symptom poor disorders recognizing in laboratory medicine.

Cross-Sectional Studies↗
PubMed1980

Lactate dehydrogenase in human renal carcinoma tissues.

Lactate dehydrogenase (LDH) activity and isoenzyme were determined in 27 human renal carcinoma (RC) tissues. Although LDH-1 and LDH-2 were predominant in the normal kidney, a completely inverted isoenzyme pattern was observed in 16 carcinomas. The others, however, showed either a normal or an incompletely inverted pattern. The LDH activity in the tumours with a completely inverted pattern was significantly higher than the activity of incompletely inverted or normal kidney pattern. It was also found that the isoenzyme pattern was more closely correlated with cell type than the grade of malignancy of the tumour, 14 out of the 16 cases of the completely inverted pattern being of the clear cell type, and 9 out of the 11 cases of incompletely inverted or normal kidney pattern being of either granular cell or mixed cell type. These results seemed to well substantiate an opinion that in clear cells anaerobic glycolysis provides a major energy source, whereas granular cells seek energy source primarily in TCA cycle and subsequent oxidative phosphorylation.

Adenocarcinoma↗
PubMed1988

Crystallization of a ternary complex of lactate dehydrogenase from Bacillus stearothermophilus.

Bacillus stearothermophilus lactate dehydrogenase was purified from an overexpressing Escherichia coli cell line. The enzyme has been crystallized in several different forms. All of these crystal forms were grown in the presence of NADH, sodium oxamate and fructose 1,6-bisphosphate. Three crystal forms have been characterized, an orthorhombic P2(1)2(1)2 (type III, a = 86 A, b = 105 A, c = 136 A) and two monoclinic P21 forms (type IV, a = 85 A, b = 118 A, c = 136 A, beta = 96 degrees; type V, a = 112 A, b = 85 A, c = 136 A, beta = 91 degrees). Precession photographs from these crystal forms are very alike, suggesting the molecular packing to be similar in all three forms. The P21 type IV crystals diffract to beyond 2 A spacing and are stable to irradiation with X-rays. A complete medium-resolution (4.7 A) dataset has been collected from a single crystal using synchrotron radiation. Rotation function studies with these data show the two tetramers of the asymmetric unit to be in very similar orientations. Higher-resolution data are being collected.

Cell Line↗
PubMed1991

Interaction of the membrane-bound D-lactate dehydrogenase of Escherichia coli with phospholipid vesicles and reconstitution of activity using a spin-labeled fatty acid as an electron acceptor: a magnetic resonance and biochemical study.

The interaction with phospholipid vesicles of the membrane-bound respiratory enzyme D-lactate dehydrogenase of Escherichia coli has been studied. Proteolytic digestion studies show that D-lactate dehydrogenase is protected from trypsin digestion to a larger extent when it interacts with phosphatidylglycerol than with phosphatidylcholine vesicles. Wild-type D-lactate dehydrogenase and mutants in which an additional tryptophan is substituted in selected areas by site-specific oligonucleotide-directed mutagenesis have been labeled with 5-fluorotryptophan. 19F nuclear magnetic resonance studies of the interaction of these labeled enzymes with small unilamellar phospholipid vesicles show that Trp 243, 340, and 361 are exposed to the lipid phase, while Trp 384, 407, and 567 are accessible to the external aqueous phase. Reconstitution of enzymatic activity in phospholipid vesicles has been studied by adding enzyme and substrate to phospholipid vesicles containing a spin-labeled fatty acid as an electron acceptor. The reduction of the doxyl group of the spin-labeled fatty acid has been monitored indirectly by nuclear magnetic resonance and directly by electron paramagnetic resonance. These results indicate that an artificial electron-transfer system can be created by mixing D-lactate dehydrogenase and D-lactate together with phospholipid vesicles containing spin-labeled fatty acids.

Amino Acid Sequence↗
PubMed1992

Crystallization and preliminary X-ray diffraction studies of two mutants of lactate dehydrogenase from Bacillus stearothermophilus.

Bacillus stearothermophilus lactate dehydrogenase, one of the most thermostable bacterial enzymes known, has had its three-dimensional structure solved, the gene coding for it has been cloned, and the protein can be readily overexpressed. Two mutants of the enzyme have been prepared. In one, Arg171 was changed to Trp (R171W) and Gln102 was changed to Arg (Q102R). In the other, the mutation Q102R was maintained, but Arg171 was changed to Tyr (R171Y). In addition, an inadvertent C97G mutant was present. Both mutants have been crystallized by the hanging drop vapor diffusion method at room temperature. Bipyrimidal crystals have been obtained against (NH4)2SO4 in 50 mM piperazine HCl buffer. The crystals belong to space group P6(2)22 (P6(4)22) (whereas the native enzyme, the structure of which has been solved by Piontek et al., Proteins 7:74-92, 1990) crystallized in the space group P6(1)) with a = 102.3 A, c = 168.6 A for the R171W, Q102R, C97G triple mutant, and a = 98.2 A; c = 162.1 A for the R171Y, Q102R, C97G mutant. These crystal forms appear to contain one-quarter of a tetramer (M(r) 135,000) in the asymmetric unit and have VM values of 3.8 and 3.3 A3/dalton, respectively). The R171W mutant diffracts to 2.5 A and the R171 Y mutant to approximately 3.5 A.

Bacterial Proteins↗
PubMed2004

Effects of N-terminal deletion mutation on rabbit muscle lactate dehydrogenase.

Deletion mutants of rabbit muscle lactate dehydrogenase (LDH) were constructed using polymerase chain reaction (PCR) to study the roles of N-terminal residues. The coding sequences of the first 5 (LD5) and 10 (LD10) amino acids of the N-terminus were deleted and the gene was inserted into the prokaryotic expression vector pET21b. The mutant enzymes were expressed in E. coli BL21/DE3 and were purified. Then their characteristics and stabilities were studied. The results showed LDH was completely inactivated when the first 10 N-terminal amino acid residues were removed, but the mutant (LD10) could have partially restored activity in the presence of structure-making ions. The removal of the first 5 and 10 N-terminal amino acid residues did not affect the aggregation state of the enzyme, that is, LD5 and LD10 were still tetramers. The stabilities of recombinant wild-type LDH (RW-LD), LD5, and LD10 were compared by incubating them at low pH, elevated temperature, and high GuHCl. The results showed that the N-terminal deletion mutants were more sensitive to denaturing environments; they were easily inactivated and unfolded. Their instability increased and their ability to refold decreased with the increased number of amino acid residues removed from the N-terminus of LDH. These results confirm that the N-terminus of LDH plays a crucial role in stabilizing the structure and in maintaining the function of the enzyme.

Amino Acid Sequence↗