Enzymes Case

factors affecting enzymes action.mechanism of enzyme action. competitive and non competitive inhibitors.Various metals, all positively charged and including zinc, iron, magnesium, manganese and copper, are known to form complexes with different enzymes or substrates. This metal-substrate-enzyme complex can aid in the orientation of the substrate in the active site, and metals are known to mediate oxidation-reduction reactions by reversible changes in their oxidation states (like Fe3+ to Fe2+).

active site - a region of an enzyme comprised of different amino acids where catalysis occurs (determined by the tertiary and quaternary structure of each enzyme)

substrate - the molecule being utilized and/or modified by a particular enzyme at its active site

co-factor - organic or inorganic molecules that are required by some enzymes for activity. These include Mg2+, Fe2+, Zn2+ and larger molecules termed co-enzymes like nicotinamide adenine dinucleotide (NAD+), coenzyme A, and many vitamins.

Enzyme activity can be altered genetically

A mutation in an enzyme can alter its substrate affinity, co-factor binding stability etc. which can be used as a diagnostic in comparison with normal enzyme

Loss of enzyme presence due to genetic mutation as detected by increased enzyme substrate and/or lack of product leading to a dysfunction

A catalyst is unaltered during the course of a reaction and functions in both the forward and reverse directions. In a chemical reaction, a catalyst increases the rate at which the reaction reaches equilibrium, though it does not change the equilibrium ratio. For a reaction to proceed from starting material to product, the chemical transformations of bond-making and bond-breaking require a minimal threshold amount of energy, termed activation energy. Generally, a catalyst serves to lower the activation energy of a particular reaction.

The rate of the reaction is determined by several factors including the concentration of substrate, temperature and pH. For most standard physiological enzymatic reactions, pH and temperature are in a defined environment (pH 6.9-7.4, 37oC). Therefore, the concentration of substrate is the critical determinant. This enzymatic rate relationship has been described mathematically by combining the equilibrium constant (the ratio of substrate and product concentrations), the free energy change and first or second-order rate theory. The net result for enzymatic reactions is that the lower the activation energy, the faster the reaction rate, and vice versa.

A reaction rate will generally

increase with increasing

Temperature due to increased

kinetic energy in the system until

a maximal