What Amino Acid Is Made to Replace Another Amino Acid $\alpha$

question 113

Multiple Choice

What amino acid is made to replace another amino acid in membrane-spanning $\alpha$ -helices by site-directed mutagenesis of the gene coding for the protein? This is done in order to determine how close together two such $\alpha$ -helices are in the structure of an integral protein.The amino acid is added to facilitate the formation of crosslinks between $\alpha$ -helices that are in close proximity.

• A)phenylalanine
• B)alanine
• C)cysteine
• D)methionine
• E)proline

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