What is enzyme specificity?

Enzyme specificity is the ability of an enzyme to identify one specific substrate from a group of chemically similar compounds. It is a molecular recognition mechanism that is based on complementary structural and conformational properties between enzymes and substrates. 

Enzymes exhibit different degrees of specificity toward their substrate. Enzyme specificity is determined by the distinctive three-dimensional structure of the enzyme's active site. This structure perfectly fits and matches the shape and chemical characteristics of its particular substrate(s).