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A protein is a large biomolecule that consists of a long sequence of amino acids linked by peptide bonds.

The structure of a protein is a three-dimensional arrangement. Theprimary structureof a protein is the amino acid sequence of the protein.

The secondary structure is the spatial arrangement organized locally that depends on the sequence of amino acids. The most common secondary structures include α helices and β sheets.

The tertiary structure is the structure of the whole polypeptide, generally stabilized by the inner hydrophobic interactions and outer hydrophilic interactions.

Some proteins have more than one polypeptide chain. Those are called the protein subunits. The quaternary structure is the spatial arrangement of more than one subunit of the proteins.

Carboxypeptidase A is a Zinc-containing pancreatic exopeptidase. It hydrolyses the peptide bonds at the C-terminal of a protein and removes the amino acids.

The light blue coils in the given structure of carboxypeptidaseArepresentsα helices, while the green color arrows represent the β pleated sheets.

The number of both α helices and β sheets in the carboxypeptidase A is 8.