Effect of Lactate Dehydrogenase Isoenzymes on the Coupled Enzymatic Assay for Alanine Aminotransferase Activity

1975 ◽  
Vol 21 (3) ◽  
pp. 330-333 ◽  
Author(s):  
Michael M Chang ◽  
Tai Wha Chung
Keyword(s):  
Lactate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Alanine Aminotransferase ◽  
Rabbit Muscle ◽  
Aminotransferase Activity ◽  
Lactate Dehydrogenase Activity ◽  
Enzymatic Assays ◽  
Substrate Specificities ◽  
Lactate Dehydrogenase Isoenzymes ◽  
Alanine Aminotransferase Activity

Abstract We show an example of the importance of specifying the form of isoenzyme and source of indicator enzymes to be used in coupled enzymatic assays. When we compared H4 (pig heart) and M4 (rabbit muscle) isoenzymes of lactate dehydrogenase for their suitability as indicator enzymes in the assay for alanine aminotransferase activity, we found that about fourfold as much M4 as H4 was required in terms of lactate dehydrogenase activity to reflect accurately equivalent amounts of alanine aminotransferase activity. Moreover, the substrate specificities of the two isoenzymes differed quantitatively.

Electrophoretic Demonstration of Three Extra Lactate Dehydrogenase Isoenzymes in the Serum of a "Normal" Individual

1974 ◽  
Vol 20 (7) ◽  
pp. 841-842 ◽  
Author(s):  
N M Papadopoulos
Keyword(s):  
Lactate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Normal Individual ◽  
Serum Lactate ◽  
Total Serum ◽  
Serum Lactate Dehydrogenase ◽  
Asymptomatic Individual ◽  
Lactate Dehydrogenase Activity ◽  
Lactate Dehydrogenase Isoenzymes

Abstract A clinically asymptomatic individual with normal total serum lactate dehydrogenase activity had an electrophoretically abnormal serum pattern for lactate dehydrogenase isoenzymes, eight isoenzyme bands being present.

New Instrument for Rapid Determination of Activities of Lactate Dehydrogenase Isoenzymes

1975 ◽  
Vol 21 (9) ◽  
pp. 1277-1281 ◽  
Author(s):  
Johannes Everse ◽  
Richard M Reich ◽  
Nathan O Kaplan ◽  
W Donald Finn
Keyword(s):  
Lactate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Electronic Device ◽  
Rapid Determination ◽  
Total Activity ◽  
Myocardial Infarctions ◽  
Lactate Dehydrogenase Activity ◽  
New Instrument ◽  
High Concentrations ◽  
Lactate Dehydrogenase Isoenzymes

Abstract Lactate dehydrogenase isoenzymes can be distinguished kinetically by the fact that isoenzyme H is strongly inhibited a few seconds after the reaction is started if high concentrations of pyruvate are present, in contrast to the M isoenzyme. A new instrument that exploits this fact can measure both the total activity and the proportion of H isoenzyme in serum or plasma in 8 to 10 s. The instrument consists of a simplified stoppedflow apparatus in which the plasma is assayed for lactate dehydrogenase activity, and an electronic device that measures the rate of the reaction at two pre-set time intervals. The first rate is taken between 0.2 and 0.4 s after the reaction is started, a time at which both isoenzymes are fully active, and at which the rate obtained thus reflects total lactate dehydrogenase activity in the plasma sample. The second rate is measured 4 to 6 s after the start of the reaction, at which time the H isoenzyme has become inhibited and the observed rate compared to the initial rate is therefore proportional to the percentage of H isoenzyme activity in the serum. These two rates are electronically displayed on two three-digit voltmeters, the first display being the total activity, the second a number proportional to the inhibited slope. The percentage of M isoenzyme can then be calculated from the initial and final rate. A total of five to six repeat assays may be done within a minute on 1 ml of plasma or serum. This instrument may be of significant value in following the progress of myocardial infarctions and other diseases.

scholarly journals Lactate dehydrogenase isoenzymes of sperm cells and testes

1969 ◽  
Vol 111 (2) ◽  
pp. 207-218 ◽  
Author(s):  
Jørgen Clausen
Keyword(s):  
Lactate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Ph Dependence ◽  
Human Sperm ◽  
Maximal Activity ◽  
Sperm Cells ◽  
Lactate Dehydrogenase Activity ◽  
Middle Piece ◽  
Lactate Dehydrogenase Isoenzymes ◽  
Concentration Ratios

1. The kinetic and metabolic properties of lactate dehydrogenase isoenzyme LDHx from human sperm cells and rat testes were studied. 2. LDHx shows a sensitivity to inhibition by stilboestrol diphosphate, urea and guanidinium chloride different from that of the LDH-H4 and LDH-M4 isoenzymes. 3. About 10 and 20% of the total lactate dehydrogenase activity of testes and sperm cells respectively were associated with particulate fractions. In sperm cells 11% was localized in the middle piece and 18·8% in the head fraction. LDHx was found in all particulate fractions of sperm cells. The middle piece contained 41·0% of total LDHx activity and showed high succinate dehydrogenase activity. 5. The pH-dependence of lactate/pyruvate and NAD+/NADH concentration ratios were estimated. Lactate dehydrogenase in sperm cells has maximal activity with NADH as coenzyme at pH7·5 and with NADPH as coenzyme at pH6·0. At pH6·0 a 10% greater oxidation of NADPH than of NADH was found. At acid pH lactate hydrogenase may function as an enzyme bringing about transhydrogenation from NADPH to NAD+. 6. In agreement with the stoicheiometry of the lactate de- hydrogenase reaction, the lactate/pyruvate concentration ratio decreased with increasing pH. 7. The lactate/pyruvate and NAD+/NADH concentration ratios were estimated with glucose, fructose and sorbitol as substrates and as a function of time after addition of these substrates. During a 20min. period after the addition of the substrates, changes in lactate/pyruvate and NAD+/NADH concentration ratios were noticed. Increasing concentration of the substrates mentioned gave rise to asymptotic increases in lactate and pyruvate. 8. Sorbitol did not act as a substrate for LDHx. 9. The findings described are consistent with the idea that LDHx is different from other known lactate dehydrogenase isoenzymes, but that it has a metabolic function similar to that of the isoenzymes of other tissues.

Reversible loss of lactate dehydrogenase isoenzymes and lactate dehydrogenase activity in patient's serum.

1988 ◽  
Vol 34 (4) ◽  
pp. 781-783
Author(s):  
R J Kraaijenhagen ◽  
E T Backer
Keyword(s):  
Lactate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Application Site ◽  
Lactate Dehydrogenase Activity ◽  
Reversible Loss ◽  
Lactate Dehydrogenase Isoenzymes

Abstract An abnormal lactate dehydrogenase (LD; EC 1.1.1.27) electrophoretogram (only one band, at the application site) and a low LD activity (7 U/L) was seen for a patient's serum during storage at 22 and 4 degrees C. Both reverted to normal when the serum was incubated at 37 degrees C.

scholarly journals The foetal development of lactate dehydrogenase isoenzymes, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase from human striated muscle

1969 ◽  
Vol 111 (2) ◽  
pp. 219-224 ◽  
Author(s):  
Jørgen Clausen ◽  
Robert Hustrulid
Keyword(s):  
Lactate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Skeletal Muscles ◽  
Muscle Fibres ◽  
Relative Distribution ◽  
Foetal Development ◽  
Lactate Dehydrogenase Activity ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Lactate Dehydrogenase Isoenzymes

1. Human foetal skeletal muscles involved in support and in periodic contractility were studied for their content of total extractable lactate dehydrogenase, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities as well as for the relative distribution of lactate dehydrogenase isoenzymes. 2. During foetal development a linear steady increase in total lactate dehydrogenase activity as well as a linear decrease in the H/M sub-unit ratio of the isoenzymes was found. 3. No significant changes were found in the activities of the enzymes of the hexose monophosphate shunt (C-6 oxidation). 4. The changes found suggest a steady increased synthesis of lactate dehydrogenase M-sub-units in human skeletal muscles during foetal development. 5. The weekly changes in the total lactate dehydrogenase activity and in lactate dehydrogenase isoenzymes are lower in muscles involved in support than in those involved in periodic contractility. 6. These findings, together with the literature available, are consistent with the morphological fact that foetal development of skeletal muscles mostly concerns the white muscle fibres and not the red muscle fibres.

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