Final answer:
Option 3, carboxypeptidase A, is the enzyme among the choices listed. Enzymes like carboxypeptidase A are proteins that increase the rate of chemical reactions in the body and exhibit high substrate specificity. Option 3 is correct.
Step-by-step explanation:
The correct answer to the question "Which of the following is an enzyme?" is option 3) carboxypeptidase A.
Enzymes are biological molecules, typically proteins, that significantly speed up the rate of virtually all of the chemical reactions that take place within cells. They are vital for life and serve a wide range of important functions in the body, such as aiding in digestion and metabolism.
Carboxypeptidase A is a specific type of peptidase enzyme that acts on peptide bonds, particularly those near the free carboxylic group, and is involved in the hydrolysis of proteins. It removes amino acids from the carboxyl end of a protein or peptide. Enzymes like trypsin and amylase have specific functions as well, such as cleaving peptide bonds of basic amino acids or specific glycosidic linkages, respectively.
Enzymes are typically named with the suffix -ase and are well known for their substrate specificity and high catalytic power. For instance, pepsin acts on peptide bonds contributed by aromatic amino acids like tyrosine, tryptophan, and phenylalanine.