GLOSSARY

Conformational Change changes spatial arrangement without necessarily changing protein sequence.

Binding, conformational adjustment, chemistry and product release are connected steps of an enzyme cycle, and each step's rate can matter. Lock-and-key is a useful simplified teaching model but incompletely represents protein flexibility; induced fit and selection among existing conformations give a more dynamic view. Tighter binding does not always produce faster turnover or more product, because chemical conversion and release must also occur.

The active site combines substrate recognition and reaction chemistry; catalytic site emphasizes reaction-performing components, while binding site emphasizes recognition. A regulatory site may be separate and alter activity through an effector. Binding away from the active site does not automatically produce pure noncompetitive inhibition. Binding location and kinetic behavior must be described separately rather than treating all distant binding as one inhibition pattern.

Enzymes lower barriers through suitable substrate orientation, active-site chemistry and transition-state stabilization. A transition state is not a stable intermediate that accumulates. Catalysis may involve proton transfer, temporary covalent bonds or metal-ion assistance; enzymes do not all use one mechanism. Mechanistic description supports biochemical understanding but alone cannot demonstrate a supplement benefit or an improvement in sports performance without relevant outcome evidence.