There are four levels that describe the structure of a protein

There are four levels that describe the structure of a protein

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There are four levels that describe the structure of a protein:  The primary structure of a protein describes the order of amino acids. Using three  letters to represent each amino acid, the primary structure for the protein antidiuretic  hormone (ADH) can be written as cys-tyr-glu-asn-cys-pro-arg-gly. The secondary structure of a protein is a three-dimensional shape that results from  hydrogen bonding between amino acids. The bonding produces a spiral (alpha helix) or a  folded plane that looks much like the pleats on a skirt (beta pleated sheet). The tertiary structure of a protein includes additional three-dimensional shaping that  results from interaction among R groups. For example, hydrophobic R groups tend to clump 
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Unformatted text preview: toward the inside of the protein, while hydrophilic R groups clump toward the outside of the protein. Additional three-dimensional shaping occurs when the amino acid cysteine bonds to another cysteine across a disulfide bond. This causes the protein to twist around the bond (Figure 6). • The quaternary structure describes a protein that is assembled from two or more separate peptide chains. The protein hemoglobin, for example, consists of four peptide chains that are held together by hydrogen bonding, interactions among R groups, and disulfide bonds. Figure 6. Disulfide bonds can dictate a protein's structure....
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