Enzymes: Protein Catalysts. Increase rates of reaction, but not consumed. Enable reactions to occur under mild conditions: e.g. temperature, pH. High reaction specificity: no side products. Activity of enzymes can be regulated. Substrate Availability of enzyme (expression, localization)
Prosthetic groups/co-enzymes usually VITAMINS!
Vitamin deficiency diseases: malfunction of enzymes
A-H + B [ AHB ] A + H-B
S ------> P
Reaction Velocity: the instantaneous rate (k) at which product is produced (or substrate disappears) mulitplied by the amount of substrate present: v = k[S]
The rate of production of product = rate of consumption of substrate.
The rate constant for the forward reaction is defined as kf or k+1 and for the reverse reaction as kr or k-1:
The velocity of the forward reaction is: vforward = k+1[S]
The velocity of the reverse reaction is: vreverse = k-1[P]
At equilibrium, the velocity of the forward reaction is equal to the reverse reaction k+1[S] = k-1[P], so there is no overall change in the distribution of S and P.
An equilibrium constant of the reaction can be defined:
Keq = [P]/[S] = k+1/k-1
This equation demonstrates that at equilibrium, the concentration of S and P reflects the relative stability (free energy difference) between S and P.