A feature of an enzyme activity with regard to the kind of substrate reacting with an enzyme to yield a product
In an enzyme activity, the substrate must bind with the enzyme to become a catalyst of a chemical reaction. And most enzymes are highly specific particularly to the nature of the substrate they bind to. Substrate specificity is one of the most essential distinctive features of enzymes. Examples of enzymes showing a very high specificity are biosynthetic enzymes such as those involved in genome replication and expression. There are certain enzymes that have varying extent of substrate specificity. For instance, there are certain hydrolases that are relatively nonspecific and then there are other hydrolases that are selective or specific in such a way that they require substrates containing particular groups. In another example, certain enzymes react with high specificity with only one substrate whereas closely related substances may react with the enzyme though they are not brought to reaction and thus act as inhibitors, e.g. succinate and malonate with succinate dehydrogenase.1
1 Karlson, P. (1965). Introduction to modern biochemistry. New York: Academic Press.