Does the effect of enzyme activity changed by the concentration of enzyme solution?

Question

concentration I means enzyme concentration in the solution

Answer 1

Since enzymes act as catalysts, the rate of the reaction might change but usually the enzyme activity itself will not change with a change in the concentration of the enzyme.

The biggest possible exception is enzymes which catalyze the hydrolysis of proteins. At very high concentrations, the enzyme might start to hydrolyze other molecules of enzyme. In this case the enzyme becomes a substrate. A change in substrate will change activity.

Answer 2

that depends also on substrate concentration. the enzyme speeds up the reaction of the substrate, so if the substrate concentration is low, the enzyme concentration doesn't particularly matter - more enzyme won't speed up the reaction because all the substrate is bound to enzymes and reacting as fast as possible. on the other hand the enzyme concentration will be rate limiting if it is lower than the substrate concentration :

http://en.wikipedia.org/wiki/Michaelis-Menten_kinetics