# Team:Paris/Modeling/Others prog

### From 2008.igem.org

## complexes

function complexes = complexes(x,y,K,n) % amount of complexes n*x + y = x_-_y in function of x, y % x, y = initial amounts of binding molecules % K = dissociation constant % n = stoechiometric coefficient of x syms z; % to treat z as a symbolic variable Eqn = ( ( x - n*z )^n )*( y - z ) - K*z; % to define the equation in whose % the amount of complexes is a root S = eval(solve( Eqn, 'z' )); % the vector of the roots Index = find ((0 < S) & (n*S < x) & (S < y) & (imag(S) == 0)); % determine % which % root is % acceptable complexes = S(Index(1)); % the result end

## hill

function compl = hill(x,K,n) % complexation nx + Y = x_-_Y when x is in large excess : % gives the ratio (x_-_Y)/(Ytotal) in function of x % x = molecule that binds to Y % K^n = dissociation constant % n = stoechiometric coefficient of x ; also known as 'cooperativity' compl = x^n/(K^n + x^n); end