Explanation

Prosthetic groups are organic compounds and are distinguished from other co-factors (non-protein constituents bound to the enzymes) in that they are tightly bound to the apoenzyme (protein portion of the enzymes). For example, in peroxidase and catalase, which catalyze the breakdown of $H_{2}O_{2}\$to$\ H_{2}O\$and$\ O_{2}$, haeme is the prosthetic group and it is the part of active site of the enzyme.