# Model of part of glycolysis (Keener and Sneyd 1998).  This model is the quasi-steady state formulation of 
# Sel'kov's (1968) model of the conversion of fructose 6-P to fructose 1,6-bisP.  The model itself does not 
# follow fructose.  Rather it looks only at the cofactors, ADP and ATP, of phosphofructokinase 1, the enzyme
# that catalyzes this reaction.  The cool thing is that ADP is both a product of the reaction and an
# activator of it, binding at both the active and regulatory sites.
#
#  Variables:
#     ATP : concentration of ATP in the cell.
#     ADP : concentration of ADP in the cell.
#
#  Parameters:
#     v  : Production rate of ATP in the cell.
#     a  : Enzyme activity.
#     b  : Decay rate of ADP in the cell.
#     g  : Number of ATP the enzyme must bind to before it is activated.
#  
#------------------------------------------------------------------------------------------------------------
# Set-up equation:
f = ATP*ADP^g/((ADP^g)*ATP + ADP^g + 1)
#------------------------------------------------------------------------------------------------------------
# Vector field:
ATP'  = v - f
ADP'  = a*f - b*ADP
#-------------------------------------------------------------------------------------------------------------
# Parameters:
p v=0.0285, b=0.1, a=1.0, g=2
#-------------------------------------------------------------------------------------------------------------
# Initial conditions: 
I ATP=0.3, ADP=0.3
#-------------------------------------------------------------------------------------------------------------
# Control stuff
@ bounds=100000, total=800, delay=10, Xlo=0, Xhi=800, Ylo=0, Yhi=1.4, MaxStore=1000000
d