SEARCH · Search PubMed

Results for “LACTATE DEHYDROGENASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources

PubMed1975

Production of racemic lactic acid in Pediococcus cerevisiae cultures by two lactate dehydrogenases.

Nicotinamide adenine dinucleotide (NAD)-dependent d(minus)-and l(plus)-lactate dehydrogenases have been partially purified 89- and 70-fold simultaneously from cell-free extracts of Pediococcus cerevisiae. Native molecular weights, as estimated from molecular sieve chromatography and electrophoresis in nondenaturing polyacrylamide gels, are 71,000 to 73,000 for d(minus)-lactate dehydrogenase and 136,000 to 139,000 for l(plus)-lactate dehydrogenase. Electrophoresis in sodium dodecyl sulfate-containing gels reveals subunits with approximate molecular weights of 37,000 to 39,000 for both enzymes. By lowering the pyruvate concentration from 5.0 to 0.5 mM, the pH optimum for pyruvate reduction by d(minus)-lactate dehydrogenase decreases from pH 8.0 to 3.6. However, l(plus)-lactate dehydrogenase displays an optimum for pyruvate reduction between pH 4.5 and 6.0 regardless of the pyruvate concentration. The enzymes obey Michaelis-Menten kinetics for both pyruvate and reduced NAD at pH 5.4 and 7.4, with increased affinity for both substrates at the acid pH. alpha-Ketobutyrate can be used as a reducible substrate, whereas oxamate has no inhibitory effect on lactate oxidation by either enzyme. Adenosine triphosphate causes inhibition of both enzymes by competition with reduced NAD. Adenosine diphosphate is also inhibitory under the same conditions, whereas NAD acts as a product inhibitor. These results are discussed with relation to the lactate isomer production during the growth cycle of P. cerevisiae.

Adenosine Triphosphate↗

PubMed1990

Macromolecular lactate dehydrogenase: an innocent bystander.

Lactate dehydrogenase (LD) activity is often increased in malignancy, and may occasionally be a useful tumor marker. In the case reported here, a persistently increased LD activity led to an extensive search for a neoplasm. Results of routine investigations were normal, but LD electrophoresis followed by gel filtration and immunofixation confirmed the presence of a circulating macromolecular LD, comprising IgAK bound to LD. Altogether it may provoke unnecessary investigations, the LD-IgA complex currently has no diagnostic significance.

Adult↗

PubMedDate not supplied

[Effect of sectioning the celiac and vagus nerves on the activity and isoenzymatic composition of rat liver lactate dehydrogenase].

Total activity of lactate dehydrogenase (LDH) was increased in rat liver cytoplasm after dissection of nervus celiacus; the enzyme activity was, however, decreased after section of nervus vagus. As showen by polyacrylamide gel electrophoresis the alterations in the enzyme activity occurred mainly due to changes in the isoenzyme LDH5, prevailing in this liver fraction. Administration of insulin did not restore the LDH activity, decreased after vagotomy. The suggestion is corroborated that the regulatory effects of sympathetic and parasympathetic nervous systems on glycolysis are of oppositely directed character.

Animals↗

PubMed1980

[Total activity and the isoenzymatic spectrum of blood serum lactate dehydrogenase in oncological patients].

Lactate dehydrogenase (LDH) isoenzyme spectrum was studied in blood serum of healthy persons (50), cancer patients (337) and patients with benign tumors and chronic inflammatory diseases (94). The total LDH activity was found to be unchanged. In patients with cancer of different localizations (63%) the LDH-5: LDH-1 coefficient turned out to be elevated. This observation allowed us to specify the range of the coefficient values from 0.07 and more, which is characteristic of cancer patients only. The corresponding values for healthy subjects and patients with benign tumors and chronic inflammatory processes would be 0.07.

Clinical Enzyme Tests↗

PubMed1995

Genetic analysis of a family of lactate dehydrogenase A subunit deficiency.

Lactate dehydrogenase A subunit (LDH-A) deficiency is an inherited metabolic myopathy of glycolysis. The severity of this disease varies from case to case. We reported non-consanguineous male sibling cases who had severe muscle pain and rhabdomyolysis during anaerobic exercise. Genetic analysis revealed 20 base pair deletion of the sixth exon of the LDH-A gene. There was no difference in the gene abnormality between our patients and previously reported female cases who had history of consanguinity and lower degree of symptoms. The differences in disease severity were not due to genomic abnormality in our two families.

Adult↗

PubMed1986

Conformational drift of dissociated lactate dehydrogenases.

Bovine and porcine lactate dehydrogenases, in solutions of 0.1-10 microM at neutral pH, dissociate into monomers upon application of hydrostatic pressures of up to 2 kbar. The dissociation was determined from observations of the polarization of fluorescence under pressure in seeming equilibrium conditions and by occasional hybridization experiments of the H4 and M4 isozymes. Decompression is followed by the rapid association of the monomers into tetramers and by slow, and sometimes incomplete, return of the enzymic activity. The dissociation curves obtained on compression and decompression differ, indicating that association results in partial loss of subunit affinity. These phenomena are attributed to a slow conformational drift that follows the loss of contact of the monomers with each other and to an even slower reversal of the drift that takes place upon reassociation.

Animals↗

PubMed1986

Conformational drift and cryoinactivation of lactate dehydrogenase.

Solutions of porcine lactate dehydrogenase of micromolar concentration kept at 4 degrees C for several days lose the greater part of their enzymic activity but recover it when returned to room temperature. The rate of spoiling decreases and the rate of recovery increases with the concentration of the solutions. The decrease in tetramer stability in the cold is shown by experiments of pressure dissociation at various temperatures and confirmed because isozyme hybridization occurs in parallel with the inactivation at low temperature but is absent at room temperature. Cold-inactivated solutions contain tetramers that dissociate much more readily than those of the fully active solutions. It is postulated that cryoinactivation, like pressure inactivation, takes place through a cycle of dissociation, conformational drift [King, L., & Weber, G. (1986) Biochemistry (second paper of three in this issue)] and reassociation into inactive tetramers.

Animals↗

PubMed1996

A rapid beta-NADH-linked fluorescence assay for lactate dehydrogenase in cellular death.

Lactate dehydrogenase (LDH) release in a common marker of cellular death. Traditionally, the fraction of LDH released has been measured using a NADH-linked UV-Vis spectrophotometric method. The limitation of this method is that samples are usually run serially and thus is time intensive. Therefore, we developed a NADH-linked LDH assay using a fluorescence plate reader that had a correlation of 0.95 with the traditional UV-Vis spectrophotometric method. Using rabbit renal proximal tubule suspensions at a concentration of 1 mg cellular protein/ml of media, the fluorescence assay can determine LDH release in 22 samples in 2 min using 12 microL of cellular homogenates and 150 microL of media. The parallel processing of samples and smaller volumes used in the fluorescence assay results in decreased analysis time and costs.

Animals↗

PubMed1976

The refolding of lactate dehydrogenase subunits and their assembly to the functional tetramer.

The renaturation process of different lactate dehydrogenase isozymes (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) from their unfolded subunits was investigated using a number of techniques. (a) kinetics of activity regain, (b) the kinetics of fluorescence change of fluoresecence change of the protein tryptophans, (c) kinetics of regain of the fluorescence properties of a covalently attached fluorescence probe (fluorescein) and (d) the kinetics of assembly, by following the intermediate oligomeric species appearing in the assembly pathway from monomers to tetramers. The results indicate that the unfolded polypeptide is converted to the active oligomeric species by the following scheme: Denatured subunit I leads to partially refolded subunit II leads to folded subunit III leads to dimer IV leads to tetramer. Step I and step II are first-order where step II is rate limiting. The ligands NAD+ and NADH accelerate step II, thus converting step I to the rate-limiting process. The fact that partially folded lactate dehydrogenase subunits are capable of co-enzyme binding may indicate the possible role of these ligands in the assembly of lactate dehydrogenase in vivo. Steps III and IV were found to be fast. The intermediate formation of an enzyme dimer which then dimerizes to the tetrameric species is found to be the major assembly pathway. Only a small portion of the lactate dehydrogenase tetramer is formed through the intermediate formation of a trimer intermediate.

Animals↗

PubMed1995

Monoclonal antibodies against lactate dehydrogenase of Plasmodium knowlesi.

Lactate dehydrogenase (LDH) of malarial parasites has been demonstrated to be biochemically and immunochemically distinct from the equivalent host enzyme. The polyclonal antibodies raised against the purified plasmodial LDH showed specificity to Plasmodium spp. Six hybridoma cell lines secreting monoclonal antibodies specific to Plasmodium knowlesi LDH have been obtained. The two monoclonal antibodies (2A3B7 and 4A6A7) showed high reactivity with LDH from simian (P. knowlesi. P. cynomolgi), human (P. falciparum, P. vivax) and rodent (P. berghei, P. yoelii) malarial parasites and did not cross-react with red cell LDH as well as with isoenzymic forms of mammalian LDH (A4, B4 and C4). One monoclonal antibody (4A6A7) strongly inhibited the enzyme activity specifically of plasmodial LDH and did not have any effect on the activity of red cell LDH. The other monoclonal (2A3B7) did not show inhibitory effect on parasite LDH. These findings as well as competitive immunoassay studies suggest the presence of at least two parasite specific epitopes on plasmodial LDH.

Animals↗

PubMed1988

Serum and leukocyte lactate dehydrogenase activity in leukaemias.

Lactate dehydrogenase (LHD) content of serum and leukocytes was examined in 42 haematologically normal healthy volunteers and in 34 patients suffering from various types of leukaemia. All patients were studied at the time of presentation and before any therapeutic intervention. Serum LDH was elevated in all types of leukaemia. In acute myeloid leukaemia (AML) a significant elevation of leukocyte LDH activity (p less than 0.005) was noted. In acute lymphoblastic leukaemia leukocyte (ALL), LDH was significantly elevated when compared to normal lymphocyte LDH (p less than 0.01) levels, but not when compared to total normal leukocyte LDH levels. In chronic leukaemias, leukocyte LDH levels were not significantly different from the normal. Comparison of LDH isoenzyme pattern in peripheral blood cells with that of serum, both in normal and in leukaemia cases showed more "M" type enzyme in the cells than in the serum. However, the "M" type enzyme was significantly elevated only in AML cases (p less than 0.005). Serum LDH and peripheral blood leukocyte count compared in normal subjects and in leukaemia cases showed no correlation.

Adult↗

PubMed1989

[Effect of inorganic anions on the activity of dental pulp lactate dehydrogenase].

Pig dental pulp lactate dehydrogenase (EC. 1.1.1.27; LDH) isozymes were separated by DEAE Sephadex A-50 column chromatography, and LDH-1 isozyme was purified by blue dextran affinity chromatography. The specific activity of pig dental pulp LDH-1 was 193.2 units/mg protein, and the purified enzyme showed a single protein band on disk electrophoresis. In this paper, we studied the effect of inorganic ions on the activity of pig dental pulp LDH-1 isozyme, and compared it with that of affected by anions. Dental pulp and heart muscle LDH-1 isozymes were inhibited at a low pyruvate concentration; otherwise, at a high pyruvate concentration, each enzyme activity was enhanced by the anions. But the effect of SO2(2-) was different from that of the other anions: SO2(2-) did not activate the enzyme at a high pyruvate concentration. In the dental pulp, the Km values for pyruvate were 1 order of magnitude smaller by SO2(2-), and 1 order higher by other anions than the control value. In the heart muscle, the Km values were not changed by anions, except by SO2(2-).

Animals↗

PubMed1973

Ionic properties of an essential histidine residue in pig heart lactate dehydrogenase.

1. Pig heart lactate dehydrogenase is inhibited by addition of one equivalent of diethyl pyrocarbonate. The inhibition is due to the acylation of a unique histidine residue which is 10-fold more reactive than free histidine. No other amino acid side chains are modified. 2. The carbethoxyhistidine residue slowly decomposes and the enzyme activity reappears. 3. The essential histidine residue is only slightly protected by the presence of NADH but is completely protected when substrate and substrate analogues bind to the enzyme-NADH complex. The protection is interpreted in terms of a model in which substrates can only bind to the enzyme in which the histidine residue is protonated and is thus not available for reaction with the acylating agent. 4. The apparent pK(a) of the histidine residue in the apoenzyme is 6.8+/-0.2. In the enzyme-NADH complex it is 6.7+/-0.2. 5. Acylated enzyme binds NADH with unchanged affinity. The enzyme is inhibited because substrates and substrate analogues cannot bind at the acylated histidine residue in the enzyme-NADH complex.

Acylation↗

PubMed2001

[Expression and immunocompetence characterization of Plasmodium falciparum lactate dehydrogenase].

OBJECTIVE: To express lactate dehydrogenase (LDH) gene of Plasmodium falciparum FCC1/HN in the E. coli TG1 and analyse its immunocompetence. METHODS: The LDH gene of the P. falciparum was specifically amplified by polymerase chain reaction, and the recovered gene fragment was cloned into pGEX-4T-1 vector for expression of fusion protein with glutathione S-transferase(GST). The recombinant plasmid was transformed into the E. coli TG1. Four mice (Kunming strain) were immunized with purified expressed protein(antigen) and the polyclonal antibodies were collected. The immunocompetence of recombinant protein was analysed by ELISA and Western-blot. RESULTS: The LDH gene of P. falciparum was successfully expressed in the E. coli TG1. The expressed protein exhibited a specific reaction with immune sera obtained from rabbits immunized with P. falciparum. The specific humoral responses were induced in mice and the titer of the specific antibody was 1:16 by two-dimensional diffusion assay. CONCLUSION: The LDH gene of P. falciparum has been successfully expressed in the E. coli TG1 and the expressed protein has high antigencity.

Animals↗

PubMed1980

Temperature and pH effects on immobilized lactate dehydrogenase kinetics.

Rabbit muscle lactate dehydrogenase (EC 1.1.1.27) was attached covalently to the inner surface of nylon tubing, and kinetic measurements made. The results were interpreted on the basis of the Kobayashi-Laidler treatment of immobilized enzymes in flow systems, various tests being applied to determine the degree of diffusion control. It was established in various ways that the degree of diffusion control increases with (a) decrease in flow rate, (b) decrease in substrate concentration, and (c) decrease in temperature. A number of quantitative relationships, predicted by the theory, were obeyed by the results, for example: (a) Km(app) varies linearly with vf-1/3, where vf is the flow rate, (b) the logarithm of the product concentration at the exit varies linearly with the logarithm of the flow rate, and (c) absolute calculations of product concentrations are in reasonable agreement with experiment. A value of 5 kcal . mol-1 is estimated for the activation energy of the diffusion processes, and of 1 kcal . mol-1 for the chemical processes. When the pH is varied the rates pass through a flat maximum, the pH dependence being less than with the free enzyme.

Animals↗

PubMed2005

Effect of ultrasonic scaling on salivary lactate dehydrogenase.

PURPOSE: To determine Lactate Dehydrogenase Activity (LDHA) in whole saliva in individuals with periodontal disease and the effect of ultrasonic scaling on this enzyme activity. METHODS: A study group of 50 patients with PD (Community Periodontal Index of Treatment Needs > or = 3) was selected at random. Half of the patients (n=25) received ultrasonic periodontal treatment (Group 1). In the other 25 patients with PD the ultrasonic scaling was not performed (Group 2). A control group was selected (Group 3) consisting of 25 adults without PD (Community Periodontal Index of Treatment Needs = 0), with age and gender distribution similar to the study group. LDHA determinations were carried out with a Cobas Mira Plus II autoanalyzer pursuant to the recommendations of the French Society of Clinical Biology. A baseline determination of LDHA was carried out on all the participants and a second determination was performed 3 months later. RESULTS: Baseline determination of LDHA was higher in patients with PD than in the control group. These differences were statistically significant (P< 0.001). LDHA was significantly reduced in patients with PD after ultrasonic scaling with respect to baseline determination (P< 0.0001). LDHA differences between Groups 2 and 3 were statistically significant (P< 0.0001), but it was not so between Groups 1 and 3.

Adult↗

PubMed2001

New insights into salivary lactate dehydrogenase of human subjects.

Lactate dehydrogenase (LDH) is a ubiquitous enzyme that plays a significant role in the clinical diagnosis of pathologic processes. The purpose of the current study was to examine LDH activity and isoenzyme profile of whole saliva and to compare it with the LDH activity of salivary glands and plasma before and after exposure to cigarette smoke (CS). The range of LDH activity in whole saliva at rest was 360 to 430 U/L. The mean +/- SEM of LDH activity in parotid and submandibular/sublingual salivary secretions was 41.3 +/- 19.2 U/L and 77.5 +/- 30.4 U/L, respectively, which implied that 75% of the whole-saliva LDH originated from an extra-salivary gland source. The profile of salivary LDH isoenzymes was found to have an entirely different pattern from that found in plasma, similar to that found in oral epithelium, indicating that the major source of salivary LDH is probably the oral epithelium-shedding cells. Therefore, salivary LDH may be evaluated for possible oral mucosal pathologies in a manner similar to that used for evaluating other tissue pathologies--such as those in heart, muscle, or liver--that can be detected in plasma. Exposure of whole saliva to CS in vitro resulted in a 41% reduction in LDH activity. However, CS exposure had no effect on LDH activity in plasma. Whole saliva, in contrast to plasma, contains redox-active metal ions such as iron and copper that may enhance LDH loss of activity. Therefore we conclude that whole saliva in the presence of CS becomes a potent protein-modifying agent that can destroy some of its endogenous components.

Adolescent↗

PubMed1981

Partial purification and characterization of lactate dehydrogenase from Plasmodium falciparum.

Lactate dehydrogenase (LDH) from Plasmodium falciparum was partially purified by two different procedures. In the first procedure, parasitized erythrocytes (80% parasitemia) were lysed, and the soluble fraction was purified on DEAE-Sephadex to separate the parasite LDH(LDH-P) from the LDH isoenzymes present in the human erythrocytes. LDH-P was then purified by high-performance liquid chromatography (HPLC) on a TSK-G-3000 SW protein column. This two-step procedure gave LDH-P with specific activity 85 micromol/min/mg protein; this represented a 700-fold increase in specific activity relative to the starting lysate. Alternatively, parasites of P. falciparum were isolated by mechanical rupture of infected erythrocytes followed by differential centrifugation. The 100,000 X g supernatant obtained after lysis of these parasites showed LDH-P specific activity 3.6 micromol/min/mg protein. This activity was free of contaminating erythrocyte LDH as determined by electrophoresis and specific staining for LDH. Further purification of LDH-P by HPLC, as before, gave material with specific activity 98 micromol/min/mg protein. Recoveries of activity on HPLC were more than 90%, demonstrating the usefulness of this procedure for the partial purification of small quantities of parasite protein. The kinetic properties of LDH-P were compared with those of two of the human isozymes, LDH-H4 and LDH-M4 . LDH-P resembles LDH-H4 in its kinetic properties: KM (NADH) is 7, 8.3 and 1.3 microM for LDH-P, LDH-H4 and LDH-M4, respectively; KM (pyruvate) is 30, 60 and 180 microM for LDH-P, LDH-H4 and LDH-M4. LDH-P differs significantly from LDH-H4 and LDH-M4 in that LDH-P is not sensitive to inhibition by high pyruvate nor sensitive to inhibition by the complex between NAD+ and pyruvate. LDH-P is inactivated within seconds by sodium deoxycholate at concentrations that do not affect LDH-H4 and slowly inactivate LDH-M4.

Animals↗