Model of 2,3-bisphosphoglycerate metabolism in the human erythrocyte based on detailed enzyme kinetic equations1: computer simulation and Metabolic Control Analysis

This is the third of three papers [see also Mulquiney, Bubb and Kuchel (1999) Biochem. J. 342, 565-578; Mulquiney and Kuchel (1999) Biochem. J. 342, 579-594] for which the general goal was to explain the regulation and control of 2,3-bisphosphoglycerate (2,3-BPG) metabolism in human erythrocytes. 2,3-BPG is a major modulator of haemoglobin oxygen affinity and hence is vital in blood oxygen transport. A detailed mathematical model of erythrocyte metabolism was presented in the first two papers. The model was refined through an iterative loop of experiment and simulation and it was used to predict outcomes that are consistent with the metabolic behaviour of the erythrocyte under a wide variety of experimental and physiological conditions. For the present paper, the model was examined using computer simulation and Metabolic Control Analysis. The analysis yielded several new insights into the regulation and control of 2,3-BPG metabolism. Specifically it was found that: (1) the feedback inhibition of hexokinase and phosphofructokinase by 2,3-BPG are equally as important as the product inhibition of 2,3-BPG synthase in controlling the normal in vivo steady-state concentration of 2,3-BPG; (2) H+ and oxygen are effective regulators of 2,3-BPG concentration and that increases in 2,3-BPG concentrations are achieved with only small changes in glycolytic rate; (3) these two effectors exert most of their influence through hexokinase and phosphofructokinase; (4) flux through the 2,3-BPG shunt changes in absolute terms in response to different energy demands placed on the cell. This response of the 2,3-BPG shunt contributes an [ATP]-stabilizing effect. A ‘cost’ of this is that 2,3-BPG concentrations are very sensitive to the energy demand of the cell and; (5) the flux through the 2,3-BPG shunt does not change in response to different non-glycolytic demands for NADH.

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Mathematical study of feedback inhibition effects on the dynamics of metabolites on the central metabolism of a yeast cell: a combination of kinetic model and metabolic control analysis

Biotechnology & Biotechnological Equipment ◽

10.1080/13102818.2019.1641148 ◽

2019 ◽

Vol 33 (1) ◽

pp. 1126-1137 ◽

Cited By ~ 1

Author(s):

Kasbawati ◽

Agnes ◽

Anisa Kalondeng ◽

Sulfahri

Keyword(s):

Kinetic Model ◽

Yeast Cell ◽

Metabolic Control ◽

Feedback Inhibition ◽

Metabolic Control Analysis ◽

Control Analysis ◽

Central Metabolism ◽

Mathematical Study

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A strategy for increasing an in vivo flux by genetic manipulations. The tryptophan system of yeast

Biochemical Journal ◽

10.1042/bj2870473 ◽

1992 ◽

Vol 287 (2) ◽

pp. 473-479 ◽

Cited By ~ 117

Author(s):

P Niederberger ◽

R Prasad ◽

G Miozzari ◽

H Kacser

Keyword(s):

Enzyme Activity ◽

Metabolic Control ◽

Enzyme Activities ◽

Metabolic Control Analysis ◽

Control Analysis ◽

Additive Effects ◽

Synthesis System ◽

Genetic Manipulations ◽

In Vivo Flux

Decreases in enzyme activity often have little effect on the flux carried by the pathway. Similarly, up-modulation of single genes, and hence of the dependent enzyme concentrations, is frequently found to be ineffective in increasing the flux in the pathway in which the enzyme occurs. This insensitivity to enzyme variation is demonstrated experimentally for five separate enzymes in the tryptophan synthesis system of yeast, first by down-modulation of the gene dose and secondly by increasing the dose using multi-copy vectors. Such a lack of response is discussed in terms of the concepts of metabolic control analysis. When these five enzymes, however, were simultaneously increased by a multi-copy vector carrying all five genes, a substantial elevation of the flux to tryptophan was observed. These findings revealed a new phenomenon, namely the more than additive effects on the flux of simultaneous elevations of several enzyme activities.

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Metabolic control analysis of hepatic glycogen synthesis in vivo

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1921694117 ◽

2020 ◽

Vol 117 (14) ◽

pp. 8166-8176 ◽

Cited By ~ 4

Author(s):

Yuichi Nozaki ◽

Max C. Petersen ◽

Dongyan Zhang ◽

Daniel F. Vatner ◽

Rachel J. Perry ◽

...

Keyword(s):

Metabolic Control ◽

Glycogen Synthesis ◽

Metabolic Control Analysis ◽

Glucose Infusion ◽

Male Rats ◽

Hepatic Insulin Resistance ◽

Hepatic Glycogen ◽

Control Analysis ◽

Rate Controlling Step

Multiple insulin-regulated enzymes participate in hepatic glycogen synthesis, and the rate-controlling step responsible for insulin stimulation of glycogen synthesis is unknown. We demonstrate that glucokinase (GCK)-mediated glucose phosphorylation is the rate-controlling step in insulin-stimulated hepatic glycogen synthesis in vivo, by use of the somatostatin pancreatic clamp technique using [13C6]glucose with metabolic control analysis (MCA) in three rat models: 1) regular chow (RC)-fed male rats (control), 2) high fat diet (HFD)-fed rats, and 3) RC-fed rats with portal vein glucose delivery at a glucose infusion rate matched to the control. During hyperinsulinemia, hyperglycemia dose-dependently increased hepatic glycogen synthesis. At similar levels of hyperinsulinemia and hyperglycemia, HFD-fed rats exhibited a decrease and portal delivery rats exhibited an increase in hepatic glycogen synthesis via the direct pathway compared with controls. However, the strong correlation between liver glucose-6-phosphate concentration and net hepatic glycogen synthetic rate was nearly identical in these three groups, suggesting that the main difference between models is the activation of GCK. MCA yielded a high control coefficient for GCK in all three groups. We confirmed these findings in studies of hepatic GCK knockdown using an antisense oligonucleotide. Reduced liver glycogen synthesis in lipid-induced hepatic insulin resistance and increased glycogen synthesis during portal glucose infusion were explained by concordant changes in translocation of GCK. Taken together, these data indicate that the rate of insulin-stimulated hepatic glycogen synthesis is controlled chiefly through GCK translocation.

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The harmony of the cell: the regulatory design of cellular processes

Essays in Biochemistry ◽

10.1042/bse0450057 ◽

2008 ◽

Vol 45 ◽

pp. 57-66 ◽

Cited By ~ 16

Author(s):

Jan-Hendrik S. Hofmeyr

Keyword(s):

Complex System ◽

Computer Simulation ◽

Enzyme Kinetics ◽

Metabolic Control ◽

Living Cell ◽

Metabolic Control Analysis ◽

Demand Analysis ◽

Control Analysis ◽

Cellular Processes ◽

Regulatory Design

The living cell is a complex system of interacting processes. The properties of the agents that facilitate these processes, such as enzymes, transporters and receptors, must be tuned to each other if the system is to behave harmoniously. The present chapter describes how the regulatory design of cellular subsystems that makes this harmonious behaviour possible can be visualized on a graph that combines the so-called log–log rate characteristics of these subsystems. The tools that are needed to create and analyse these graphs are metabolic control analysis, supply-demand analysis, enzyme kinetics and computer simulation.

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Model of 2,3-bisphosphoglycerate metabolism in the human erythrocyte based on detailed enzyme kinetic equations1: computer simulation and Metabolic Control Analysis

Biochemical Journal ◽

10.1042/0264-6021:3420597 ◽

1999 ◽

Vol 342 (3) ◽

pp. 597 ◽

Cited By ~ 28

Author(s):

Peter J. MULQUINEY ◽

Philip W. KUCHEL

Keyword(s):

Computer Simulation ◽

Metabolic Control ◽

Human Erythrocyte ◽

Metabolic Control Analysis ◽

Control Analysis ◽

Enzyme Kinetic

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Acute and chronic effects of bupivacaine on muscle energetics during contraction in vivo: a modular metabolic control analysis

Biochemical Journal ◽

10.1042/bj20112011 ◽

2012 ◽

Vol 444 (2) ◽

pp. 315-321 ◽

Cited By ~ 2

Author(s):

Laurent M. Arsac ◽

Karine Nouette-Gaulain ◽

Sylvain Miraux ◽

Veronique Deschodt-Arsac ◽

Rodrigue Rossignol ◽

...

Keyword(s):

Metabolic Control ◽

Metabolic Control Analysis ◽

Mitochondrial Activity ◽

Resonance Spectroscopy ◽

Control Analysis ◽

Muscle Energetics ◽

Chronic Effects ◽

Muscle Energy Metabolism ◽

System Variables

Bupivacaine is a widely used anaesthetic injected locally in clinical practice for short-term neurotransmission blockade. However, persistent side effects on mitochondrial integrity have been demonstrated in muscle parts surrounding the injection site. We use the precise language of metabolic control analysis in the present study to describe in vivo consequences of bupivacaine injection on muscle energetics during contraction. We define a model system of muscle energy metabolism in rats with a sciatic nerve catheter that consists of two modules of reactions, ATP/PCr (phosphocreatine) supply and ATP/PCr demand, linked by the common intermediate PCr detected in vivo by 31P-MRS (magnetic resonance spectroscopy). Measured system variables were [PCr] (intermediate) and contraction (flux). We first applied regulation analysis to quantify acute effects of bupivacaine. After bupivacaine injection, contraction decreased by 15.7% and, concomitantly, [PCr] increased by 11.2%. The regulation analysis quantified that demand was in fact directly inhibited by bupivacaine (−21.3%), causing an increase in PCr. This increase in PCr indirectly reduced mitochondrial activity (−22.4%). Globally, the decrease in contractions was almost fully explained by inhibition of demand (−17.0%) without significant effect through energy supply. Finally we applied elasticity analysis to quantify chronic effects of bupivacaine iterative injections. The absence of a difference in elasticities obtained in treated rats when compared with healthy control rats clearly shows the absence of dysfunction in energetic control of muscle contraction energetics. The present study constitutes the first and direct evidence that bupivacaine myotoxicity is compromised by other factors during contraction in vivo, and illustrates the interest of modular approaches to appreciate simple rules governing bioenergetic systems when affected by drugs.

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