The matching between enzyme and substrate can vary in specificity. Most enzymes have absolute specificity in that they will only bind to a specific substrate that matches the characteristics of its active site. Other enzymes may exhibit lower specificity and bind to multiple substrates to catalyze a reaction. 

Enzymes exhibit four types of specificity: 

• Absolute specificity,in which an enzyme exclusively binds to one specific substrate and catalyzes only one reaction with that substrate
• Group specificity, in which an enzyme reacts only with molecules that contain specific functional groups such as methyls, phosphate groups, or aromatic structures
• Bond specificity,in which an enzyme recognizes only certain types of chemical bonds such as a peptide bond
• Stereochemical specificity,in which an enzyme recognizes a substrate’s optical activity of orientation