What are the four types of enzyme specificity:

1. Absolute specificity– An enzyme is said to have absolute specificity when it catalyzes only one substrate and reaction.
2. Group specificity– If an enzyme acts only on molecules that possess specific functional groups such as amino, phosphate, and methyl groups, it has group specificity.
3. Linkage specificity– If an enzyme acts on a specific type of chemical bond regardless of the remaining molecular structure, it has linkage specificity. 
4. Stereochemical specificity– An enzyme that acts on a certain optical or steric isomer has stereochemical specificity.