Action Of Lactate Dehydrogenase Research Articles

Glycolysis and the significance of lactate in traumatic brain injury

In traumatic brain injury (TBI) patients, elevation of the brain extracellular lactate concentration and the lactate/pyruvate ratio are well-recognized, and are associated statistically with unfavorable clinical outcome. Brain extracellular lactate was conventionally regarded as a waste product of glucose, when glucose is metabolized via glycolysis (Embden-Meyerhof-Parnas pathway) to pyruvate, followed by conversion to lactate by the action of lactate dehydrogenase, and export of lactate into the extracellular fluid. In TBI, glycolytic lactate is ascribed to hypoxia or mitochondrial dysfunction, although the precise nature of the latter is incompletely understood. Seemingly in contrast to lactate's association with unfavorable outcome is a growing body of evidence that lactate can be beneficial. The idea that the brain can utilize lactate by feeding into the tricarboxylic acid (TCA) cycle of neurons, first published two decades ago, has become known as the astrocyte-neuron lactate shuttle hypothesis. Direct evidence of brain utilization of lactate was first obtained 5 years ago in a cerebral microdialysis study in TBI patients, where administration of 13C-labeled lactate via the microdialysis catheter and simultaneous collection of the emerging microdialysates, with 13C NMR analysis, revealed 13C labeling in glutamine consistent with lactate utilization via the TCA cycle. This suggests that where neurons are too damaged to utilize the lactate produced from glucose by astrocytes, i.e., uncoupling of neuronal and glial metabolism, high extracellular levels of lactate would accumulate, explaining the association between high lactate and poor outcome. Recently, an intravenous exogenous lactate supplementation study in TBI patients revealed evidence for a beneficial effect judged by surrogate endpoints. Here we review the current state of knowledge about glycolysis and lactate in TBI, how it can be measured in patients, and whether it can be modulated to achieve better clinical outcome.

반추동물용 활성제로서 Lactobacillus sp. FFy111-1이 생산한 Lactate Dehydrogenase의 특성에 관한 연구

본 연구는 미생물 유래 lactate dehydrogenase(LDH)를 이용하여 반추위내에 lactate 축적을 예바하기 위한 기능성 검증을 목적으로 수행되었다. 미생물의 효소활성에 영향을 주는 많은 반추위내 요인들 중 대표적인 것들 즉, 온도, pH, 휘발성지방산(VFAs) 그리고 금속이온들이 Lactobacillus sp. FFy111-1의 LDH 효소활성에 미치는 영향과, 반추위액내 축적된 lactate에 대한 LDH 작용을 평가하였다. Lactobacillus sp. FFy111-1의 LDH는 각각 pH 7.5와 40<TEX>$^{\circ}C$</TEX>에서 가장 좋은 효소 활력을 보였다. 온도 안정성은 30<TEX>$^{\circ}C$</TEX>에서 가장 좋게 나타났으며 30<TEX>${\sim}$</TEX>50<TEX>$^{\circ}C$</TEX>의 온도 범위에서는 80% 이상의 활성을 유지하였다. 그리고 pH 안정성은 pH 7.0과 8.0에서 모두 가장 좋은 결과를 나타냈으며 pH 6.1과 6.5에서 64% 이상의 효소활성을 유지하였다. VFAs와 금속이온이 LDH에 미치는 영향을 측정하였을 때, VFAs 처리는 LDH 효소활성을 억제하였으나, NaCl과 <TEX>$CuSO_4$</TEX>를 제외한 금속 이온 처리에서는 LDH 효소활성이 증가되었다. 특히 2mM <TEX>$BaCl_2$</TEX>와 <TEX>$MgSO_4$</TEX>로 처리 하였을 때 가각 비처리 효소활성의 127과 124% 수준까지 효소활성이 증진되었다. 반추위액내 축적된 lactate에 대한 LDH 작용을 보기 위하여 Lactobacillus sp. FFy111-1의 효소를 산중독 반추위액에 처리하였을 때 lactate의 농도가 무처리 반추위액내 lactate 농도의 78% 수준으로 감소하였다(P<0.05). 이와 같은 lactate 감소는 LDH의 작용에 의해 나타난 현상으로 정제된 D,L-LDH를 첨가한 실험결과(34% lactate)에서 입증되었다(P<0.05). 이상의 연구 결과들을 고려하여 볼 때 미생물이 생성한 LDH는 반추위내 축적된 lactate를 감소시킬 수 있는 충분한 가능성을 갖고 있다고 사료된다. 또한 더 좋은 미생물의 발굴과 반추위 환경에서 LDH 활성을 높이기 위한 기술개발이 LDH 효소의 실제적 응용을 위하여 필수적이다. The objective of this experiment is to study the possibility of lactate dehydrogenase(LDH) enzyme to prevent lactate accumulation in the rumen, For understanding capacity of bacterial LDH in rumen environments, this study was conducted to explore the effects of temperature, pH, VFAs and metal ions on Lactobacillus sp. FFy111-1's LDH activity, and the LDH activation in rumen fluid accumulated lactate. The optimum pH and temperature of LDH were pH 7.5 and 40<TEX>$^{\circ}C$</TEX>, respectively. The LDH activity had a good thennostability at range from 30 to 50<TEX>$^{\circ}C$</TEX>. The highest pH stability of the enzyme was at ranges from pH 7.0 to 8.0 and the enzyme activities showed above 64% level of non-treated one at pH 6.0 and 6.5. The LDH was inactivated by VFAs treatments but was enhanced by metal ion treatments without NaCl and <TEX>$CuSO_4$</TEX> Especially, the LDH activity was increased to 127% and 124% of its original activity by 2 mM of <TEX>$BaCl_2$</TEX> and <TEX>$MnSO_4$</TEX>, addition, respectively. When the acidic rumen fluid was treated by LDH enzyme of Lactobacillus sp. FFy111-1, the lactate concentration in the rumen fluid was lower compared with non-treated rumen fluid(P<0.05). This lactate reduction was resulted from an action of LDH. It was proved by result of purified D,L-LDH addition that showed the lowest lactate concentration among the treatments(P<0.05). Although further investigation of microbial LDH and ruminal lactate is needed, these findings suggest that the bacterial LDH has the potential capability to decrease the lactate accumulated in an acidic rumen fluid. Also, screening of super LDH producing bacteria and technical development for improving enzyme activity in rumen environment are essential keys for practical application.

Determinations of lactate and lactate dehydrogenase activity in serum with the flow injection analysis system involving immobilized enzyme column and chemiluminescence

The methods for the highly sensitive flow injection analysis of lactate and lactate dehydrogenase (LDH) activity in serum using immobilized enzymes in column form and chemiluminescence detection which does not require a blank correction are described. The methods were based on the determination of chemiluminescence formed by the reaction of a luminol-ferricyanide mixture with hydrogen peroxide. This hydrogen peroxide was produced by the lactate oxidase (LOD) reaction from lactate, which was in serum or was produced by the action of LDH in serum. The action of LDH in a flow injection analysis system was performed for 2 min in an incubation coil placed parallel to the substrate-buffer line between the LOD column and the LOD/catalase column. Endogenous lactate in serum was removed by an immobilized LOD/catalase column prior to the action of LDH. The present method gave perfect linearity of the data up to 5.6 mmol/liter for lactate and 1840 IU/liter for LDH activity with satisfactory precision, reproducibility, and accurate reaction recoveries. The results from the lactate and LDH activity correlated satisfactorily with those obtained by other well-established methods.

Subunit cooperativity in the action of lactate dehydrogenase

Interspecific hybrids of pig heart lactate dehydrogenase ( l-lactate:NAD + oxidoreductase, EC 1.1.1.27) isozyme((PH) 4) and chicken heart lactate dehydrogenase isozyme((CH) 4) were obtained by freezing and thawing. Heat inactivation profiles of the interspecific hybrids revealed: 1. 1.|At 70°, the pig heart lactate dehydrogenase ((PH) 4) is appreciably less stable than the chicken heart lactate dehydrogenase ((CH) 4). 2. 2.|The hybrid isozyme ((CH) 3(PH) 1) is completely inactivated along with the inactivation of the pig heart isozyme ((PH) 4). To explain these observations, four types of models (“active monomer” model, “active dimer” model, “active trimer” model and “active tetramer” model) were tested. The theoretical heat inactivation profiles deduced from the “active dimer” model gives the best fit to the experimental heat inactivation profiles. This fact suggests that two protomers act in cooperation as an active dimer in a tetrameric molecule of lactate dehydrogenase.