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Results for “LACTATE DEHYDROGENASE”

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PubMed1976

Correlation analysis of Baker's studies on enzyme inhibition. 2. Chymotrypsin, trypsin, thymidine phosphorylase, uridine phosphorylase, thymidylate synthetase, cytosine nucleoside deaminase, dihydrofolate reductase, malate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, and glyceraldehyde-phosphate dehydrogenase.

The inhibitory activity of 1058 inhibitors of the title enzymes has been formulated in 13 equations correlating chemical structure with inhibitory potency. Two types of regions in enzymes have been defined by means of pi and molar refractivity constants. The use of indicator variables has been extensively developed to suggest special enzyme-ligand interactions. Several examples are given of the use of correlation equations in comparing structural features of different systems.

Animals↗
PubMed1998

Effects of cold acclimation on the activity levels of creatine kinase, lactate dehydrogenase and lactate dehydrogenase isoenzymes in various tissues of the rat.

The effects of cold acclimation on the activity levels of creatine kinase, lactate dehydrogenase and lactate dehydrogenase isoenzymes in various tissues/ organs of the rat (Rattus norvegicus) were investigated. Male Sprague-Dawley rats were divided into two groups. One group was housed at 4+/-1 degrees C (experimental group) and the other at 24+/-1 degrees C (control group) for six months. The rats were housed in single cages and had access to food and water ad libitum. The tissues/organs investigated were heart, liver, lung, kidney, gastrocnemius muscle and interscapular brown adipose tissue as well as serum. With the exception of lung, (which showed a decrease of 24%) total creatine kinase activity levels were significantly increased (P< 0.05) in all the tissues/organs investigated (17-51%) as well as serum (34%), in cold acclimated animals. Cold acclimation also resulted in significantly increased (P< 0.05) activity levels of lactate dehydrogenase in all the tissues/organs investigated (14-24%) as well as serum (35%). Cold exposure resulted in an increase of the activity levels of all the detectable isoenzymes of lactate dehydrogenase, although not always significant, in all the tissues/organs investigated as well as serum. The M(4)tetramer of lactate dehydrogenase was the only detectable isoenzyme in serum.

Acclimatization↗
PubMed1990

Serum lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase and ratio of alpha-hydroxybutyrate dehydrogenase to lactate dehydrogenase in testicular tumours.

Serum levels of Lactate Dehydrogenase (LDH), alpha-Hydroxybutyrate Dehydrogenase (HBDH) and the relative ratio of alpha-Hydroxybutyrate Dehydrogenase to Lactate Dehydrogenase (HBDH/LDH) were determined in 51 cases of histologically proved testicular germ cell tumors and 40 healthy controls. Serum LDH and HBDH levels were found to be raised in both seminomatous and non-seminomatous germ cell tumors. The ratio of HBDH/LDH was found to be statistically significant in seminomas and insignificant in non-seminomatous germ cell tumors. Furthermore, the levels of LDH and HBDH showed a fall, following treatment indicating response to therapy. Serum LDH and HBDH could both be used as tumor markers in the diagnosis of testicular germ cell tumors as well as prognostic indicators in monitoring therapy, HBDH, being more specific in monitoring therapy as compared to serum LDH.

Adolescent↗
PubMedDate not supplied

[Glucose-6-phosphate dehydrogenase and lactate dehydrogenase activities and lactate dehydrogenase isoenzyme spectrum in human myocardium after sudden death caused by acute alcohol intoxication and ischemic heart disease].

Alterations in activities of lactate- and glucose-6-phosphate dehydrogenases and in the LDHisozyme spectra in human heart muscle after sudden death, caused either by acute ethanol intoxication or by ischemic heart disease, were characterized by inhibition of aerobic oxidation and activation of the glycolytic pathway of energy formation.

Adult↗
PubMed1988

Usefulness of lactate dehydrogenase and lactate dehydrogenase isoenzymes for diagnosis of acute myocardial infarction.

The usefulness of lactate dehydrogenase (LD) and LD isoenzymes in the diagnosis of acute myocardial infarction (AMI) is controversial. The present study reviewed 507 consecutive patients in whom creatine kinase, creatine kinase isoenzymes, LD and LD isoenzymes were ordered over a 1-month period. Of these, 249 had an insufficient number of serial enzyme determinations to establish a laboratory diagnosis of AMI. After excluding an additional 11 patients for other reasons, 247 patients remained for analysis. Of these, only 2 (0.8%) had myocardial infarction by standard clinical criteria with normal creatine kinase and creatine kinase-MB but elevated LD and abnormal LD isoenzymes. Seven patients (7 of 247, 2.8%) had false-positive LD isoenzymes. Thus, the routine use of LD and LD isoenzymes was of no use in most patients (96%) and led to the incorrect diagnosis of AMI more than 3 times as often as it helped with a correct diagnosis. Total 1-month charges for all the LD and LD isoenzymes obtained equalled +42,450. Therefore, it appears that LD and LD isoenzymes are not routinely useful in the diagnosis of AMI and may result in considerable unnecessary expense. It is suggested that LD and LD isoenzymes be ordered only under suspicion of late presentation (greater than 48 hours) of AMI.

Creatine Kinase↗
PubMed1998

Selective inhibitors of human lactate dehydrogenases and lactate dehydrogenase from the malarial parasite Plasmodium falciparum.

Derivatives of the sesquiterpene 8-deoxyhemigossylic acid (2, 3-dihydroxy-6-methyl-4-(1-methylethyl)-1-naphthoic acid) were synthesized that contained altered alkyl groups in the 4-position and contained alkyl or aralkyl groups in the 7-position. These substituted dihydroxynaphthoic acids are selective inhibitors of human lactate dehydrogenase-H (LDH-H) and LDH-M and of lactate dehydrogenase from the malarial parasite Plasmodium falciparum (pLDH). All inhibitors are competitive with the binding of NADH. Selectivity for LDH-H, LDH-M, or pLDH is strongly dependent upon the groups that are in the 4- and 7-positions of the dihydroxynaphthoic acid backbone. Dissociation constants as low as 50 nM were observed, with selectivity as high as 400-fold.

Animals↗
PubMed1980

Onchocerca volvulus: effect of suramin on lactate dehydrogenase and malate dehydrogenase.

Lactate dehydrogenase and malate dehydrogenases were partially purified and characterized from adult O. volvulus. The molecular weight of lactate dehydrogenase was determined to be 130 000, those of malate dehydrogenase I and II to be 120 000 and 65 000, respectively. The activities of both malate dehydrogenases and of the lactate dehydrogenase were strongly inhibited by suramin. The inhibition constants were determined to be in the range of 2 microM to 5 microM. The type of inhibition was found to be competitive with respect to the coenzyme NADH and to be non-competitive to the substrates. It is suggested that the mode of action of suramin in the therapy of Onchocerciasis might depend on the blokkade of reoxidation of NADH produced within the glycolytic pathway.

Animals↗
PubMed1992

Single amino acid substitutions can further increase the stability of a thermophilic L-lactate dehydrogenase.

Lactate dehydrogenases are of considerable interest as stereospecific catalysts in the chemical preparation of enantiomerically pure alpha-hydroxyacid synthons. For such applications in synthetic organic chemistry it would be desirable to have enzymes which tolerate elevated temperatures for prolonged reaction times, to increase productivity and to extend their applicability to poor substrates. Here, two examples are reported of significant thermostabilizations, induced by site-directed mutagenesis, of an already thermostable protein, the L-lactate dehydrogenase (EC 1.1.1.27, 35 kDa per monomer subunit) from Bacillus stearothermophilus. Thermal inactivation of this enzyme is accompanied by irreversible unfolding of the native protein structure. The replacement of Arg171 by Tyr stabilizes the enzyme against thermal inactivation and unfolding. This stabilizing effect appears to be based on improved interactions between the subunits in the core of the active dimeric or tetrameric forms of the enzyme. The thermal stability of L-lactate dehydrogenase variants with an active site Arg residue, either in the 171 (wild-type) or in the 102 position, is further increased by sulfate ions. The two stabilizing effects are additive, as found for the Arg171Tyr/Gln102Arg double mutant, for which the stability of the protein in 100 mM sulfate solution reaches that of L-lactate dehydrogenases from extreme thermophiles. All mutant proteins retain significant catalytic activity, both in the presence and absence of stabilizing salts, and are viable catalysts in preparative scale reactions.

Calorimetry↗
PubMed2001

Structural basis for altered activity of M- and H-isozyme forms of human lactate dehydrogenase.

Lactate dehydrogenase (LDH) interconverts pyruvate and lactate with concomitant interconversion of NADH and NAD(+). Although crystal structures of a variety of LDH have previously been described, a notable absence has been any of the three known human forms of this glycolytic enzyme. We have now determined the crystal structures of two isoforms of human LDH-the M form, predominantly found in muscle; and the H form, found mainly in cardiac muscle. Both structures have been crystallized as ternary complexes in the presence of the NADH cofactor and oxamate, a substrate-like inhibitor. Although each of these isoforms has different kinetic properties, the domain structure, subunit association, and active-site regions are indistinguishable between the two structures. The pK(a) that governs the K(M) for pyruvate for the two isozymes is found to differ by about 0.94 pH units, consistent with variation in pK(a) of the active-site histidine. The close similarity of these crystal structures suggests the distinctive activity of these enzyme isoforms is likely to result directly from variation of charged surface residues peripheral to the active site, a hypothesis supported by electrostatic calculations based on each structure. Proteins 2001;43:175-185.

Crystallization↗
PubMed1997

A further study of seminal plasma: lactate dehydrogenase and lactate dehydrogenase-X activities and diluted semen absorbance.

Activities of total lactate dehydrogenase, which plays an important role in providing energy for cell metabolism, lactate dehydrogenase-X, an isoenzyme of lactate dehydrogenase supposed to be specific for germinal epithelium activity, diluted semen absorbance and some other properties have been measured in 51 seminal plasma samples. Aiming to study its clinical use as a marker of seminiferous epithelium activity, determination of isoenzyme-X and investigation of correlation between it and the spermiogram properties were carried out. Besides lactate dehydrogenase and lactate dehydrogenase-X activity, their ratio and diluted semen absorbance were correlated with the different properties of the spermiogram, the best correlation of the enzymes being obtained with the total sperm count and motile sperm count. Correlation of diluted semen absorbance with the total sperm count and motile sperm count was also noted, whereas it did not correlate with sperm concentration and motility rate. The data suggests the clinical utility of these properties as reliable markers for both germinal activity and spermatozoid quality when "total sperm count" and "mobile sperm count" are used to define sperm properties instead of just sperm concentration and motility rate.

Biomarkers↗
PubMed1989

Interaction between glyceraldehyde-3-phosphate-dehydrogenase and lactate dehydrogenase.

Physical interaction between rabbit muscle glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase was detected by means of matrix immobilization technique. Glyceraldehyde-3-phosphate dehydrogenase covalently bound to CNBr-activated Sepharose 4B was capable of forming a complex with soluble lactate dehydrogenase with a stoichiometry of 0.8 mole of lactate dehydrogenase per mole of glyceraldehyde-3-phosphate dehydrogenase and KD of 0.385 microM at pH 6.5. The bienzyme association weakened when pH changed to 7.0 (the KD increased to 1.25 microM).

Animals↗
PubMed2004

Diagnosing melanoma patients entering American Joint Committee on Cancer stage IV, C-reactive protein in serum is superior to lactate dehydrogenase.

Lactate dehydrogenase (LDH) in serum has recently been introduced into the American Joint Committee on Cancer (AJCC) staging system for cutaneous melanoma because of its prognostic value. We hypothesised LDH to be of value in discriminating melanoma patients entering AJCC stage IV from patients staying in AJCC stages I, II or III. Lactate dehydrogenase was compared to the acute phase protein C-reactive protein (CRP), which we observed to reflect the course of melanoma metastasis in a previous report. In this prospective study, we measured LDH and CRP in the serum of 91 consecutive melanoma patients progressing into AJCC stage IV in comparison to 125 patients staying in AJCC stages I, II or III. Comparing distributions of the parameters by median values and quartiles by Mann-Whitney test, LDH was not significantly elevated in patients entering AJCC stage IV melanoma (P=0.785), whereas CRP was (P<0.001). Analysing the sensitivity and the specificity jointly by the areas under the receiver operating characteristics curves (ROC-AUC), LDH did not discriminate between the defined groups of patients (AUC=0.491; 95% confidence interval, 0.410, 0.581), whereas CRP did (AUC=0.933; 95% confidence interval, 0.900, 0.966; P<0.001). Upon logistic regression analysis to calculate the ROC-AUC values upon the predictive probabilities, LDH provided no additional information to CRP. Choosing a cutoff point of 3.0 mg l(-1), CRP yielded a sensitivity of 0.769 together with a specificity of 0.904 in diagnosing AJCC stage IV entry. Altogether, for first diagnosing AJCC stage IV melanoma, CRP is the superior serum marker when compared to the conventional LDH.

Aged↗
PubMed1978

Kidney in the aging cat: hexokinase, aldolase, L-alpha-glycerophosphate dehydrogenase, and lactate dehydrogenase histochemistry.

Hexokinase, aldolase, L-alpha-glycerophosphate dehydrogenase, and lactate dehydrogenase activities were determined in the kidney of the aging cat. Kidneys from 24 domestic cats 2 months to 7.5 years old in 6 age groups were examined by light microscopic and histochemical methods. Enzyme activities in anatomic components of the kidney were assessed on a quantitative basis for evaluation of mean activity between the age groups. In the cats with advancing age, renal components generally had stable activity. A significant (P less than 0.05) increase in hexokinase activity occurred with advancing age in the ascending part of the renal loop (Henle's loop) and in the distal convoluted tubule. Significant (P less than 0.05) increases in aldolase activity with aging were in cortical connective tissue, internal part of the glomerular capsule (podocytes), distal convoluted tubule, and convoluted segment (Pi) of the proximal portion of the nephron tubule. L-alpha-glycerophosphate dehydrogenase and lactate dehydrogenase activity increased significantly with aging in the convoluted (Pi) segment of the proximal portion of the nephron tubule.

Aging↗