GLOSSARY

Aminotransferase (Transaminase) catalyzes amino-group transfer.

Official enzyme classification is reaction-based and includes oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases and translocases. A common name does not necessarily specify every reaction detail or protein identity. Precise work also requires substrate, product, tissue and isoform information. These classes describe kinds of work rather than ranking enzymes by importance or potency for exercise, so classification alone cannot prescribe a nutritional intervention.

Name endings provide clues but cannot replace checking the reaction. Synthase can name synthetic activity across classes, so the shortcut that synthases never involve ATP is unreliable. Traditional synthetase usage is restricted to ligases coupled to nucleotide-triphosphate cleavage. Historical names, recommended names and classification assignments can differ; the actual catalyzed reaction is the reference for interpretation rather than a spelling rule alone.

An enzyme accelerates a reaction by lowering its activation barrier, without changing the final equilibrium or reaction free-energy difference. It is not consumed overall during a catalytic cycle, although it can be degraded or inactivated. Most enzymes are proteins, but catalytic RNA also exists. More enzyme increases reaction rate only when other constraints allow it; substrate supply, products and conditions still matter.

Specificity may concern substrate identity, reaction type or molecular stereochemistry; these are related but distinct properties. Some enzymes accept several related substrates while others have a narrower range. A family name alone cannot establish every member's exact function. Nutritionally, a similar molecule or possible binding does not prove effective processing through the intended pathway; correct substrate, reaction and conditions must be considered together.

A cofactor is a nonprotein component needed by some enzymes and may be an inorganic ion or an organic molecule. A coenzyme is organic, while a prosthetic group is generally tightly associated. Apoenzyme denotes protein lacking a required cofactor, and holoenzyme the complete active form. Binding strength and role must be specified: not every substance near an enzyme is its essential cofactor.

Measured activity is conversion per time under assay conditions rather than simply protein abundance. A substrate-rich assay may reveal potential capacity, while living tissue has different constraints and regulation. Units, tissue normalization and preparation methods are needed for comparison. Blood activity is not identical to intramuscular activity; laboratory changes require exercise timing, symptoms and tissue origin rather than being read as direct performance measures or a standalone diagnosis.