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Oxidation of lactate by human serum
Clinica Chimica Acta; International Journal of Clinical Chemistry
|September 6, 1976
Summary
Lactate dehydrogenase (LDH) enzyme activity in human serum varies with pH. Different LDH isoenzymes show distinct kinetic behaviors, with M types active at lower pH and H types at higher pH.
Area of Science:
- Biochemistry
- Enzymology
- Human Physiology
Background:
- Lactate dehydrogenase (LDH) is a crucial enzyme in cellular metabolism, catalyzing the interconversion of lactate and pyruvate.
- LDH exists as various isoenzymes with differing electrophoretic mobilities and kinetic properties.
- Understanding LDH isoenzyme behavior is vital for interpreting clinical diagnostics and metabolic studies.
Purpose of the Study:
- To investigate the kinetics of lactate oxidation by human serum lactate dehydrogenase.
- To examine the differential activity of LDH isoenzymes across a range of pH values.
- To elucidate the impact of pH on the functional characteristics of distinct LDH entities.
Main Methods:
- Enzyme kinetics assays were performed on human serum samples.
- Lactate oxidation was measured using spectrophotometric methods.
- The influence of varying pH conditions on enzyme activity was systematically analyzed.
Main Results:
- Human serum LDH exhibits pH-dependent activity profiles.
- Faster-migrating LDH isoenzymes demonstrate optimal activity at higher pH values.
- Slower-migrating LDH isoenzymes, including M type, display reduced activity at higher pH, while H type isoenzymes are partially inactivated at lower pH.
Conclusions:
- The kinetic properties of human serum lactate dehydrogenase are significantly modulated by pH.
- Differential pH optima for LDH isoenzymes explain their varying activities in physiological and pathological conditions.
- These findings contribute to a deeper understanding of LDH function in human serum and its diagnostic relevance.