clear all

% Plot Michaelis-Menten speed vs substrate behavior in the presence and 
% absence of an uncompetitive inhibitor.  
%
% Executes properly on MATLAB version 9.4.0.813654 (R2018a).
% Executes mostly properly on OCTAVE version 4.2.1.
% Joshua C. Vaughan 3/6/2023

Km = 5; % mM
Vmax = 10; % mM/sec
I_Ki = 1; % unitless fraction of [I] over K_I.
S = linspace(0,60,2^6); % mM

% Michaelis-Menten basic kinetics
v_mm = Vmax*S./(Km+S);
v_uncomp = Vmax*S./(Km + S*(1+I_Ki));

% create basic v vs [S] plot

ax_lw = 2;
pl_lw = 2;
ax_fs = 24;
la_fs = 24;
ti_fs = 20;
fontname = 'Arial';

figure(1); clf; set(gcf,'color',[1 1 1])
plot(S,v_mm,'k-',S,v_uncomp,'r-','linewidth',2);
hold on
plot([min(S) max(S)],Vmax*[1 1],'--','linewidth',2,'color',0.5*[1 1 1]); 
hold off

set(gca,'fontname',fontname)
set(gca,'tickdir','out')
set(gca,'linewidth',2)
xlabel('[S], mM','fontsize',ax_fs)
ylabel('{\itv} (mM/sec)','fontsize',ax_fs)
set(gca,'fontsize',ax_fs)
xlim([0 max(S)])
ylim([0 11])
title('Uncomp.-Inhib., {\itK}_M=5 mM, [I]/{\itK}_{I\prime}=1','fontsize',ti_fs)

legend('uninhibited','inhibited','location','southeast')
