Which of the following is changed in a reaction by the action of an enzyme?

Well during an enzyme catalyzed reaction the enzyme bonds with a specific substrate at the active site. This is called an enzyme-substrate complex. The substrate is converted into a specific product, but the enzyme remains unchanged. Enzymes accelerate reactions by factors of at least a million.Enzymes are not used up in a chemical reaction. Usually, the enzyme will "reset" and be ready to use in another reaction. This is due to the fact that enzymes are proteins, and their shape is what they use in a chemical reaction. Initially, the enzyme has a particular shape. Something happens to the enzyme (usually a shape change, called a conformation change, brought on by the presence of two or more chemical reactants), and the enzyme catalyzes the reaction. After the reaction is catalyzed, the product is released, and the enzyme can "relax." This means it goes back to its normal shape, ready to do it all over again

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