Toward theoretical investigation of mitochondrial threshold effect : development of E-Cell SRLMM(Semi-Rat Liver Mitochondria Model)

Nayuta Iwata

Bioinformatics Program, Graduate School of Media and Governance, Keio University, Fujisawa, 252-8520, Japan

Abstract:

Here weI propose the architecture of SRLMM(Semi-Rat Liver Mitochondria Model (SRLMM) to represent the mitochondrial threshold effect based on Yugi’s model¹⁶. Previous studies of mitochondrial mathematical models by Wilson²¹⁴, Bohnensack³¹⁵, Korzeniewski⁴¹⁹, Magnus⁵²⁰, Cortassa⁶²¹, and Yugi¹⁶ were compared to develop SRLMM. The kinetic properties, particularlyespecially kinetic equations, of the TCA cycle in rat liver wereare difficult to collect.

ミトコンドリア閾値現象を再現するために柚木氏のミトコンドリアモデルをベースにしたラット肝臓ミトコンドリアモデル（SRLMM）のアーキテクチャについて論ずる。SRLMMを構築するために、Wilson, Bohnensack, Korzeniewski, Magnus, Cortassa, Yugiらによって考案されたミトコンドリアモデルの比較検討分析を行った。またTCAサイクルをラット肝臓ミトコンドリアのみで構築するには速度式、パラメータなどが不足しているために困難であることが判明した。

Introduction:

Recently several aspects of mitochondrial function have been studied recentlyrecently, such as key roles in apotosis⁷⁶⁴, free radical production⁸⁶⁵, and calcium signalling⁹⁶⁶. Beside these arising topics, the mitochondrial metabolism has long been studied because mammalian mitochondrial function is generally acceptedpresented as the central pathway for energy metabolism.

The phenotypic manifestation of the mitochondrial genetic defect occurs only when a threshold level is exceeded. This phenomenon has been named the ‘phenotypic threshold effect’. The phenotypic threshold effect can be characterized by following features: (i) a low proportion of wild-type mtDNA allows a normal phenotype to be maintained, however (ii) a small decrease in this proportion below a threshold value alters the phenotype¹⁰².

Many previous works haves observed the threshold effect. Bai et alet al. demonstrated that a point mutation in mtDNA diminishes synthesis rate of complex I subunit only when the proportion of mutant mRNA is greater than 40%¹¹¹. The compensation of theon metabolic defects by mitochondria fusion is one of the possibility for the explanation of the mitochondrial threshold effect. Attardi and Hayashi ^57,59 both agree on the potential of mitochondria to fuse and mix^12,13. The compensation of mitochondria fusion on metabolic defect in mitochondria is one of the possibility for the explanation of the mitochondrial threshold effect. Although both authors agree on the mitochondrial fusionHowever, they observed striking difference on the frequency of fusion which provides transmitochondrial complementation. Attardi and co-workers^60,61,62 regard complementation as a rare process^14,15,16, whereas Hayashi and collegues^59,63 believe that it is a general phenomenon^13,17.

The phenotypic threshold effect is classified in five5 levels: transcription, translation, enzyme activity, biochemical level and cell activity¹⁰². For instance, James et alet al. used human cell lines with various levels of complex I inhibition to show that mitochondrial respiration was impaired only when the inhibition of complex I activity was greater than 85%¹⁸³. Letterier et alet al. has observed that a decrease in complex IV activity had to exceed a criticaltirical value (approx. 75% inhibition) before a decrease in the mitochondrial respiration could be observed¹⁹⁴. These results cleary demonstrate clearly the existence of a biochemical threshold effect for the expression of the respiratory chain deficiencies and mitochondrial energy production.

WithinAmong such many studies of mitochondrial threshold effect, the theoretical explanations has not beenareis not advocated. Rossignol et alet al. has postulated that the threshold curves can be distinguish into two types²⁰⁵. Figure 1 shows the two types of threshold curves. Type I threshold curves present a plateau phase followed by a steep breakage allowing a precise determination of the threshold value, whereas type II are characterized by smoother curves where the breakage is no longer evident and where a precise threshold value is difficult to determine.

Figure 1. Two types of threshold curves

To provideTo give a theoretical explanation on mitochondrial threshold effect, development of a model based on previous study is attempted in this work. I want to develop a model based on previous study.

In this article, I discuss the architecture of a mitochondrial metabolism model to verify a hypothesis : “ The respiratory chain complexes presenting Type II threshold curve possess major control on the respiratory chain activity, while the complexes which present Type I do not”.

The dynamic mitochondrial kinetic model proposed by Yugi and Tomita containing the kinetic data measured in various species, such as bBovine hHeart, bBovine lLiver, cChicken lLiver, pPig hHeart, pPig Lliver, rRat bBrain, rRat hHeart and rRat lLiver¹⁶. However, the mitochondrial quantitative properties vary according to tissue and species. For instance, the concentration of adenine nucleotide translocator in rat liver mitochondria is 290 pmol/mg proteins, whereas 1600 pmol/mg proteins in rat muscle mitochondria²⁰⁵. Rossignol et alet al. has observed that the threshold curves of the oxidative phosphorylation complexes vary accoding to tissues and species²⁰⁵. These mitochondrial metabolic features require the development of the necessitate usme to develop a model using kinetic properties from identical species and tissues.

In this article, I discuss the architecture of a mitochondrial metabolism model to verify a hypothesis which is: “ The respiratory chain complexes presenting Type II threshold curve possess major control on the respiratory chain activity, while the complexes which present Type I do not”.

In this work I propose the architecture of appropriate mitochondrial model based on Yugi’s model. I indicate that current Yugi’s model is not appropriatesufficient for clarifying mitochondrial threshold effect. The concept of SRLMM(Semi-Rat Liver Mitochondrial Model) is also discussed to verify the hypothesis.

Results:

The data of the respiratory chain and the TCA cycle were collected from published articles. Wilson, Bohnensack, Korzeniewski, Magnus, Cortassa, and Yugi have proposed the mathematical mitochondrial models. The features of these six6 models are listed in Table 12. From Table 12, the reactions which satisfy my purpose isare apparent: Cytochrome c oxidase from Wilson, Adenine nucleotide translocator from Bohnensack, ATP synthase from Cortassa and the proton buffering effect from Korzeniewski.

To validate the hypothesis described above, each complexe of the respiratory chain must be represented in detail. Each model has specific features of the respiratory chain.

Wilson et al. has proposed the mathematical model of cytochrome c oxidase including the effect of oxygen concentration¹⁴. The model agreed fairly well with experimentally measured [ATP]/[ADP][Pi] and [NAD+]/[NADH] ratio. However, their model does not consider the dynamics of other part of the respiratory chain, such as NADH:ubiquinone oxidoreductase, cytochrome c oxidoreductase and, adenine nucleotide translocator.

The respiratory chain model of Bohnensack et al. contain the the function of energy-transforming units of mitochondria, i.e. the respiratory chain, ATP synthase, translocators of phosphate and of adenine nucleotides, are described^3,21,22,23. It is shown in their work that the predicted behaviour is in accordance with the experimental data which refers to O₂ consumption and the ratio of [ATP]/[ADP] incubated with glutamate, succinate and rotenone. In particular, the rate equation of adenine nucleotide translocator faithfully reflects the translocation of ADP and ATP. However, the process which oxidize NADH and cytochrome c are described in first order kinetics. Furthermore, NADH:ubiquinone oxidoreductase, cytochrome c oxidoreductase, are represented by one equation.

One of the most largest and detailed dynamic models of the oxidative phosphorylation has been developed by Korzeniewski et al. In their model, the substrate dehydrogenation, cytochrome oxidase, the proton motive force, ATP synthase, adenine nucleotide translocator, phosphate carrier, adenylate kinase, internal and external ATP consumption⁴ are taken into account⁴. The consideration of proton buffering effect avoids rapid changes in matrix proton concentration. Although the model described a good qualitative and quantitative agreement with experimental results, abstraction of NADH:ubiquinone oxidoreductase and cytochrome c oxidoreductase was performed as well as Bohnensack. In addition, the TCA cycle and succinate dehydrogenase, known as Complex II of the respiratory chain, are not considered.

Magnus and Keizer, Cortassa et al., have proposed the mathematical model of mitochondrial energy metabolism in combination with calcium concentration^5,6. The purpose of their models are to study the mitochondrial metabolism of dynamics in β-cell and cardiac cell respectively.

Yugi and Tomita, developed the model of mitochondrial metabolism in a whole organelle scale¹. Model contains the respiratory chain, the TCA cycle, the fatty-acid β-oxidation, and the inner-membrane metabolite system. Their model consists of 58 enzyme reactions and 117 metabolites, that are the largest model ever proposed ( though Animar-Beurton et al.²⁴ are trying to propose larger scale model, it is still under construction). Although, the size of the model is fairly large, the kinetic properties used in this model vary in many species and tissues as described above. Wilson’s model mainly deals with Cytochrome c oxidase. His concept of oxygen consumption is fairly well in dealing with oxygen concentration. Since the oxygen concentration is measured in many experiments, it is possible to compare the simulation results and experimental data in terms of O₂ consumption. Adenine nucleotide translocator is famous not only Bohnensack’s model but the one proposed by Kramer et al⁴⁸. For my purpose, Bohnensack’s model is suitable because adenine nucleotide translocator is in accordance with the experiment of rat liver mitochondria. Korzeniewski consider the buffering effect of proton motive force. Their model agreed well with experimental data. The phosphorylation of ADP by ATP synthase utilize the proton motive force between the respiratory chain and the ATP synthase. ATP synthase of Cortassa’s model is an extension of the ATP synthase of Magnus in terms of the proton motive force between matrix and inter-membrane space. Because Magnus’ model is agreed with the experimental data of rat liver mitochondria, the ATP synthase of Cortassa would be sufficient for my purpose.

Table 12.: A comparison of mitochondrial models

	CI	CIII		CIV	ANT	Proton	TCA	CV	Tissue
Wilson	−−	−−		＋＋	−−	−−	−−	−−	RLM
Bohnensack	−　Combined			−	＋＋	−	−−	−	RLM
Korzeniewski	−　Combined			＋	＋	＋＋	−−	−	PRLM
Magnus	−　Combined				＋	−	−−	＋	PRLM
Cortassa	−　Combined				＋	−	＋	＋＋	CM
Yugi	＋		＋	−*	＋	−−	＋	＋	Mammal

The abbreviations used are: CI, NADH:ubiquinone oxidoreductase; CIII, Cytochrome c oxidoreductase; CIV, Cytochrome c oxidase; ANT, Adenine nucleotide translocator; Proton, Proton pump; TCA, Tricarboxylic acid cycle; CV, ATP synthase; RLM, Rat Liver Mitochondria; PRLM, Partially Rat Liver Mitochondria; CM, Cardiac Mitochondria. ― ― denotes that the process is not contained; −denotes that the process is contained, however, it is not recommended to use because the kinetic mechanism does not match with ourmy purpose; ＋ denotes that the process satisfy is contained with good agreement with ourmy purpose; ＋＋ denotes that the process is best suited for ourmy purpose. Combined denote that the complexes are assumed to be one reaction. * denotes oxygen concentration is not included.

The TCA cycle , pyruvate dehydrogenase complex, and pyruvate carboxylase are the circular energy metabolic system consisting of the 11 enzymes. The kineticexperimental data for sixof 6 enzymes out of the 11 enzymes were collected from published previous articles, which are partially concerned with the rRat lLiver mMitochondria. Supplementary Table 3Table6 in APPENDIX is the kinetic properties of citrate synthase. “Kaccoa” is the Michaelis constant of Acetyl-CoA. Though the kinetic parameters measured in Matsuoka et alet al. and, Moriyama et alet al.^2534,26-35 . are rat heart and rat liver, respectively, the value of “Kaccoa” is 5.0μM and 2.8μM. This small difference of the parameter valuess can be assumed to be the same value. On the other hand, although the rRat lLiver is used in the kinetic study of Shepherd et alet al.²⁷³⁶,, the value is six6-fold higher than the one with Moriyama et alet al. Likewise, from Supplementary Table 22 in APPENDIX, the kinetic properties of pyruvate dehydrogenase complex are shown. The Michaelis constant forof pyruvate, named “Kpyr”, in poricine liver and rat liver are only the difference of 2-fold.25μM and 56μM, respectively. It is only the difference of 2-fold.

Discussion:

Most of the enzyme kinetic studiesy were performed during the 1960s and the 1970s. Once the kinetic properties of an enzyme is observed in any species, subsequent studiesy is on the enzyme often dealt with the same species. For instance, once the kinetic properties of NAD-isocitrate dehydrogenase have been observerd in poricine and bovine ^{28,29,30,3142,49,41,55}, subsequent study mostly use the same species³²⁵⁴. This tendency can be also seen in the kinetic equations. For instance, Head et alet al.³³⁴⁰ , assumed the kinetic equation of Mussel Mytilus edulis L, Random-Orderd Bi Bi, as the equation which is derived in Bovine heart previously³⁴⁵⁶. Hence, even if the kinetic constant of an enzyme is measured in rat liver mitochondria, kinetic equation measured in rat liver is difficult to collect if the enzyme is previously measured in different species. In the case of citrate synthase, some kinetic properties do not vary according to tissue or species. These comparison of different species that do not provide considerable influence isto examine whether it provides considerable influences are necessary for the architecture of my mitochondrial model.

Since the chemiosmotic theory of Mitchel in 1961, several mathematical models of respiratory chain have been proposed³⁵⁶⁸. Though these model agreed with experimental data, most of them derived their equations phenomenologically. Fortunately, the theoretical models of Wilson, Bohnensack, and Korzeniewski are agreed with the experiment of the rat liver mitochondria. Although, the concept of Magnus and Keizer aimed at pancreatic β-cell mitochondria, their theoretical results are compared with the experiment of rat liver mitochondria. Therefore, it is appropriate to assume their model as rat liver mitochondria. In fact, in their article⁵²⁰. , they postulated that “Although the model was developed with specific application to the pancreatic β-cell in mind, it may have application to mitochondrial Ca2+ handling in other cell types in which Ca2+ uptake by mitochondria has been shown to be important” ⁵. ATP synthase from Cortassa’s model is largely based on the ATP synthase equation of Magnus’’s model. Because Magnus’ model agreed with the experiment of rRat lLiver mMitochondria as referred to above, it is appropriate to utilize ATP synthase from Cortassa’s model. The kinetic equation of Complex I and Complex III are included in^{3650 ,3751} as in Yugi’s model though these equation is derived from bBovine hHeart.

Methods:

I postulated that the TCA cycle, the respiratory chain, pyruvate carrier, and the malate-aspartate shuttle are essential systems to represent threshold effect. Because most of the experimental results of biochemical threshold curves are shown in the respiratory rate against the inhibition rate of any complex, the respiratory chain is an inevitable reactions in order to observe the biochemical threshold effect. NADH:ubiquinone oxidoreductase oxidizes NADH for the high energy electron and proton pumping. The malate-aspartate shuttle and pyruvate carrier are for the entrance of the high energy source. Generally, the respiratory rate is measured under incubation with several substrates such as pyruvate and malate. These substrates are oxidized throughout the TCA cycle. To observe the accordance between the theoretical model and the experimental results, these entrances and the TCA cycle should be included. Pyruvate carrier and malate-shuttle are for the entrance of energy source, TCA cycle and respiratory chain are for the central energy metabolism in mitochondria.I Aalso I assumed other systems such as, urea cycle and fatty acid β-oxidation, do not provide considerable influences on the threshold effect. Many experimental data of mitochondrial metabolism, such as rate equations, kinetic parameters, and control coefficients, were measured using rat livers^387,3913. Therefore the species and tissues for the mitochondrial model are rat -lLiver, respectively. In Figure 2, the pathway mapconcept of rat liver mitochondria model is shown.

Fig2. The pathway map of Rat Liver Mitochondria Model. The figure of rat and hepatocyte are quoted from^52,53, respectively.

In the model constructing process, information of hepatocyte is showen in Table 21.

Table 21. :The fundamental information

The explanation of each value	The value of each explanation
Number of mitochondria per hepatocyte	800mt/hepatocyte^40^3
The volume of mitochondrion	0.43x10^-15/l^4138
The protein concentration of mitochondriaon	400mg/ml^4239
Number of cell contained in liver	2.3x10^6 cell / mg body weight

Respiratory Chain:

To validate the hypothesis described above, each complexes of respiratory chain must be represented in detail. Although several authors proposed the mathematical models of oxidative phosphorylation, each model has specific features of the respiratory chain.

Wilson et al has proposed the mathematical model of cytochrome c oxidase including the effect of oxygen concentration¹⁴. The model agreed fairly well with experimentally measured ATP. /ADP. Pi. and NAD+. /NADH. ratio. However, their model does not consider the dynamics of other part of respiratory chain, such as NADH:ubiquinone oxidoreductase, cytochrome c oxidoreductase, adenine nucleotide translocator.

The respiratory chain model of Bohnensack et al contain the the function of energy-transforming units of mitochondria, i.e. respiratory chain, ATP synthase, translocators of phosphate and of adenine nucleotides, are described by equations^15,18. It is shown in their work that the predicted behaviour is in good agreement with the experimental data. Especially, the rate equation of adenine nucleotide translocator faithfully reflects the translocation of ADP and ATP. Although their model contains major part of oxidative phosphorylation, the process which oxidize NADH and cytochrome c are described in first order kinetics. Furthermore, NADH:ubiquinone oxidoreductase, cytochrome c oxidoreductase, are represented by one equation.

One of the most largest and detailed dynamic models of the oxidative phosphorylation has been developed by Korzeniewski et al. In their model, the substrate dehydrogenation, cytochrome oxidase, proton motive force, ATP-synthase, ATP/ADP carrier, phosphate carrier, adenylate kinase, internal and external ATP consumption¹⁹ are taken into account. The consideration of proton buffering effect avoids rapid changes in matrix proton concentration. Although the model described a good qualitative and quantitative agreement with experimental results, abstraction of NADH:ubiquinone oxidoreductase and cytochrome c oxidoreductase was performed similarly to Bohnensack. In addition, TCA cycle and succinate dehydrogenase, known as Complex II of respiratory chain, are not considered.

Magnus and Keizer, Cortassa et al, have proposed the mathematical model of mitochondrial energy metabolism in combination with calcium concentration^20,21. The purpose of their models are to study the mitochondrial metabolism of dynamics in β-cell and cardiac cell respectively.

Yugi and Tomita, developed the model of mitochondrial metabolism in a whole organelle scale⁶. Model contains respiratory chain, TCA cycle, fatty-acid β-oxidation, and inner-membrane metabolite system. Their model consists of 58 enzyme reactions and 117 metabolites, that are the largest model ever proposed ( though Animar-Beurton et al⁴⁷. are trying to propose larger scale model, it is still under construction). Although, the size of the model is fairly large, the kinetic properties used in this model vary in many species and tissues as described above.

Tricarboxylic acid cycle:

The kinetic properties of the TCA cycle were quoted from the articles and the eEnzyme database BRENDA⁴³⁶⁷. Even though the numerous data are accumulated in BRENDA, few kinetic data of rat liver mitochondria were includedinvolved. Therefore, all the data are quoted from published articles. The enzymes that I have collected are listed below.

・Pyruvate carboxylase

・Pyruvate dehydrogenase complex

・Citrate synthase

・NAD-isocitrate dehydrogenase

・NADP-isocitrate dehydrogenase

・2-oxoglutarate dehydrogenase complex

The kinetic parameters of these six enzymes were collected from previous articles. Detailed information of the six enzymes are listed in Supplementary InformationAPPENDIX.

Future works:

The architecture of SRLMM and the data of TCA cycle, respiratory chain in rat liver mitochondria has been discussed. At last I will postulate the remaining tasks to represent the mitochondrial threshold effect.

・ Complex I, Complex III

・ Remaining 4 enzymes in TCA cycle: Succinyl CoA synthase, Succinate dehydrogenase, Fumarase, Malate dehydrogenase

・ Pyruvate carrier

・ Malate-Aspartate shuttle

Acknowledgement:

I thank Katsuyuki Yugi and Yoichi Nakayama for benefical advise on my work. At last, I would like to thank Masaru Tomita for the wonderful environment to proceed my study.

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Supplementary InformationAPPENDIX:

Supplementary Table 14.: Kinetic properties of Pyruvate Carboxylase

Pyruvate Carboxylase EC:6.4.1.1		Pyruvate Carboxylase EC:6.4.1.1
KcF 63.3/s^2244
Kpyr 0.53mM^2244
Kipyr 0.99mM^2244
Kpi ×
Kipi 6mM^2244
KcR 7.5/s^2244
Kco2 2.5mM^2244
Kico2 26mM^2244
Koxa ×
Kioxa ×
Katp .082mM^2244, 0.044mM^4523
Kiatp 0.18mM^2244
Kadp ×
MW 130000Da^24
Kipi 6mM^4523
ProteinConc 18uM^4725
AcoA 0.5nmol/mg protein
CoA 1.2nmol/mg protein
Pyr 0.1umol/mg protein^4826
Tissue	All data is measured in rat liver mitochondria. Data that doesn’t refer to the species and tissue are measured in Rat Liver Mitochondria.
Kinetic Equation

Supplementary TableTable 25. :Kinetic properties of Pyruvate Dehydrogenase Complex

Pyruvate Dehydrogenase Complex EC:1.2.4.1+2.3.1.12+1.8.1.4
Pyruvate+CoA+NAD⇔NADH+Acetyl-CoA+Co2
Vmax 0.00173M/s^4927, 0.006M/s^5028. 0.0047M/s( poricine liver)^5129
Kcf 0.125/s^5230
Kpyr 56uM^5331. 0.33mM^5432, 25uM( data from poricine liver)^5129
Kpyr 56uM^5331, 0.33mM^5432, 25uM( data from poricine liver)^5129
Pyr 49.41M^5533
Oxa 0.872093M^5533
MW 9000KD
Tissue	RLM. Data that doesn’t refer to the species and tissue are measured in Rat Liver Mitochondria.
Kinetic Equation

Supplementary Table 3Table6. :The kinetic properties of citrate synthase

Citrate Synthase EC:2.3.3.1		AcetylCoA+Oxaloacetate⇔Citrate+CoA
Kaccoa 5.0uM(rat heart)^2534, 2.8uM^2635, 16.3uM^2736
Kiacoa 5.0uM(rat heart)^2534
Koxa 4.5uM(rat heart)^2534, 3.6uM^2635, 1.99uM^2736
Ki oxa 4.5uM(rat heart)^2534
Kcoa 39uM(rat heart)^2534
Kicoa 56uM(rat heart)^2534
Kcit 3mM(rat heart)^2534
Kicit 4.3mM(rat heart)^2534
Kiatp 0.7mM (rat heart)^2534.^2635
MW 100000Da
AcoA 0.5nmol/mg protein^4826
CoA 1.2nmol/mg protein^4826
Oxa 1uM^2635
Tissue	RLM and RHM. Data that doesn’t refer to the species and tissue are measured in Rat Liver Mitochondria.
Kinetic Equation
Comments	Matsuoka et alet al.^2534. , indicate the kinetic constants from rat liver and rat heart appear to be identical with citrate synthase.

Supplementary TableTable 47.: Kinetic properties of NADP-Isocitrate dehydrogenase

NADP-Isocitrate dehydrogenase(EC:1.1.1.42)
isocitrate+NADP(+)⇔2-oxoglutarate+NADPH+Co2+H(+)
Knadp 3.0uM(Mussel Mytilus edulis L)^3340
Kisocit 3.2uM(Mussel Mytilus edulis L)^3340
KnadpD 2.9uM(Mussel Mytilus edulis L)^3340
KisocitD 3.2uM(Mussel Mytilus edulis L)^3340
KIq 9.2uM(Mussel Mytilus edulis L)^3340
Kiq 9.7uM(Mussel Mytilus edulis L)^3340
KIq 23.6uM(Mussel Mytilus edulis L)^3340.
MW 61000DA
Isocit 142uM^2841.
Kinetic equation	Random ordered bibi v=Vmax*{1+(Ka/A)*(1+Q/KIq)+Kb/B+(Kia*Kb)/(A*B)*(1+Q/Kiq)}^-1+Vmax*{1+Ka/A+(Kb/B)*(1+P/KIp)+(Kia*Kb)/(A*B)*(a+P/Kip)}^3340. (Mussel Mytilus edulis L)
Tissue	Most of data are measured in Mussel Mytilus edulis L. Data that doesn’t refer to the species and tissue are measured in Rat Liver Mitochondria.
Comments	Head et alet al. report that the kinetic equation measured in Bovine heart mitochondria and Mussel Mytilus edulis are the identical.

Supplementary TableTable 59.: Kinetic properties of NAD-Isocitrate dehydrogenase

NAD-Isocitrate dehydrogenase(EC:1.1.1.41)
isocitrate+NAD(+)→2-oxoglutarate+NADH+Co2+H(+)
Kisocit 1.5mM(poricine liver)^2942.
Kiatp 0.9mM(poricine liver)^2942.
Kinadph 0.02mM(poricine liver)^2942.
Knad 0.2mM(poricine liver)^2942.
Vmax 11.46uM/s(poricine liver)^2942.
MW 160000DA
2-oxoglutarate 1.322mM^5643.
Tissue	Poricine Liver. Data that doesn’t refer to the species and tissue are measured in Rat Liver Mitochondria.

Supplementary Table Table610.: Kinetic properties of 2-oxoglutarate dehydrogenase complex

2-oxoglutarate dehydrogenase complex EC:1.2.4.2
CoA+NAD+α-ketoglutarate→SucCoA+NADH
Vmax 0.027M/s^5744. , 0.031M/s(poricine liver)^5744.
Kcf 720/s (poricine liver)^5845.
Kcoa 1.8uM(poricine liver)^5744. , 0.1uM(poricine heart)^5946.
Kisuccoa 2.7uM(poricine liver)^5744.
Koxoglutarate 0.013mM(poricine heart)^5845.
Knad 4.5uM (poricine heart)^5845.
NADH 0.92M^5744.
SucCoA 0.68M^5744.
CoA 0.468M^5744.
MW 2700000DA
Kinetic equation	V=(Vmax*(CoA/SucCoA))/((Ka/Ki)+(CoA/sucCoA)) (poricine heart)^5744.
Tissue	Mainly poricine heart. Data that doesn’t refer to the species and tissue are measured in Rat Liver Mitochondria.
Comments	The kinetic equation was derived in the medium containing 2-oxoglutarate.

Write the kinetic equation of each process by above authors here?

Over simplified description

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