Question

How to distinguish between harmone and enzyme?why insulin is a harmone and not enzyme?

Answer 1

: Enzymes and hormones have only similarity interms of their role in biological processes otherwise both are far different in composition, mode of action and retaining the original form post reaction. Hormones have versatile composition from protein to steroids whereas enzymes are mostly protein in nature except few exceptions. Hormones mostly act at distant sites, away from their synthesis sites whereas enzymes mostly act nearby to their synthesis sites. Hormones participates in biochemical reactions and changes its original chemical nature where as enzymes only alter the rate of biological reaction and remain unchanged chemically at the end of reaction. Enzymes have very precise reaction and substrate specificity where as hormones may have versatile biochemical reactivity.
A hormone is a substance produced by a person ( or animal, plant etc) which is distributed by some mechanism, e.g. blood stream or sap flow to specific cells or tissue in that body and which regulates some function of those cells or tissues. An enzyme is a substance produced by a person(or animal, plant etc) which acts to facilitate or influence a specific biochemical reaction in cells or tissues of that body. Insulin is an example of the former.