Model number

Comparison of 1-sided and 2 sided Michaelis-Menten transporters in a two compartment model without flow.



Figure3: Determining Vmax and Km from initial velocity: The quantity, VmaxEstB = V2*B2/t.max is plotted (Black Lines) against B1+B2. The uppermost point of each nearly vertical line is an estimate of the velocity of the transporter between 0 and 1 second. VmaxEstB equals approximately V2*dB2/dt = PSeffective*(B1-B2).

As the Michaelis-Menten transporter becomes saturated (increasing values of B1+B2 ranging over 6 orders of magnitude), the uppermost points of the vertical lines asymptotically approach Vmax (Green Line). Half of the value, Vmax/2 (Red line) intersects the upper outline of these vertical lines where B1+B2 = Km (dashed Blue line).

Two types of a saturable Michaelis-Menten transporter are considered in this two compartment model without flow--a one sided transporter for solute A and a two-sided transporter for solute B. The model for solute A is cis- side driven. Concentration of A in V1, A1, determines the fractional saturation, PSa/PSmax, where PSmax is Vmax/Km, and

PSa = PSmax/(1 + A1/Km).

The model for solute B is cis-trans driven. Concentration of B in both V1 and V2, B1 and B2 respectively, determine the fractional saturation, where PSmax is Vmax/Km and

PSb = PSmax/(1 + B1/Km + B2/Km).


     One sided Michaelis-Menten Transporter



     Ordinary Differential Equations



     Initial Conditions



     Two sided Michaelis-Menten Transporter




     Ordinary Differential Equations



     Initial Conditions



The equations for this model may be viewed by running the JSim model applet and clicking on the Source tab at the bottom left of JSim's Run Time graphical user interface. The equations are written in JSim's Mathematical Modeling Language (MML). See the Introduction to MML and the MML Reference Manual. Additional documentation for MML can be found by using the search option at the Physiome home page.

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 Klingenberg M. Membrane protein oligomeric structure and transport function. Nature 290: 449-454, 1981.

 Stein WD. The Movement of Molecules across Cell Membranes. New York: Academic Press, 1967.

 Stein WD. Transport and Diffusion across Cell Membranes. Orlando, Florida: Academic Press Inc., 1986.

 Wilbrandt W and Rosenberg T. The concept of carrier transport and its corollaries in pharmacology. 
 Pharmacol Rev 13: 109-183, 1961.

 Schwartz LM, Bukowski TR, Ploger JD, and Bassingthwaighte JB. Endothelial adenosin 
 transporter characterization in perfused guinea pig hearts. Am J Physiol Heart 
 Circ Physiol 279: H1502-H1511, 2000. 
Key terms
1 sided
2 sided
initial velocity

Please cite in any publication for which this software is used and send one reprint to the address given below:
The National Simulation Resource, Director J. B. Bassingthwaighte, Department of Bioengineering, University of Washington, Seattle WA 98195-5061.

Model development and archiving support at provided by the following grants: NIH U01HL122199 Analyzing the Cardiac Power Grid, 09/15/2015 - 05/31/2020, NIH/NIBIB BE08407 Software Integration, JSim and SBW 6/1/09-5/31/13; NIH/NHLBI T15 HL88516-01 Modeling for Heart, Lung and Blood: From Cell to Organ, 4/1/07-3/31/11; NSF BES-0506477 Adaptive Multi-Scale Model Simulation, 8/15/05-7/31/08; NIH/NHLBI R01 HL073598 Core 3: 3D Imaging and Computer Modeling of the Respiratory Tract, 9/1/04-8/31/09; as well as prior support from NIH/NCRR P41 RR01243 Simulation Resource in Circulatory Mass Transport and Exchange, 12/1/1980-11/30/01 and NIH/NIBIB R01 EB001973 JSim: A Simulation Analysis Platform, 3/1/02-2/28/07.