A catalyst is a substance which speeds up a chemical reaction but remains unchanged itself at the end. Thus, enzymes alter the rates of chemical reactions without themselves being chemically changed at the end of the reaction.
Answer: enzymes change the Keq for chemical reactions.
Explanation: many enzymes change shape slightly when substrate binds. reactions occur at the "active site" of enzymes, where a precise 3D orientation of amino acids is an important feature of catalysis.
