What are the protein molecules that make possible chemical reactions in living things.

An enzyme is a protein that speeds up a biochemical reaction. It is a biological catalyst. An enzyme generally works by reducing the amount of activation energy needed to start the reaction.

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Enzymes are proteins that speed up reactions by reducing the activation energy. Each enzyme typically binds only one substrate. Enzymes are not consumed during a reaction; instead they are available to bind new substrates and catalyze the same reaction repeatedly.

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The light is great source of energy