A protein that speeds up a specific chemical reaction without undergoing changes itself is called

Biocatalyst

Explanation:

The metabolism or a chemical reaction is a characteristic feature of the living organisms to survive. The biological chemical reactions involve the formation of bond and bombarding of element atoms so takes time and becomes slow.

The living organism formed the protein molecules which could speed up the reactions called a catalyst.

The catalyst is the tertiary globular structures of proteins which possess a pore called active site to which the substrate binds temporarily as well as lowers the activation energy of the chemical reaction.

Thus, Biocatalyst is the correct answer.