3. Alanine scanning is a technique to determine the importance of each amino aci

Question

3. Alanine scanning is a technique to determine the importance of each amino acid to the function of the protein. This technique uses site directed mutagenesis to create a series of mutants, each of which changes a single amino acid to alanine. If the mutant protein maintains comparable function to the original (wild type protein, this indicates that the mutated amino acid is not essential. However, if the function decreases or is lost, there are several possible effects. For example, certain mutations of the primary structure are so disruptive, the protein is targeted for degradation by the unfolded protein response (UPR). Because the protein is degraded immediately after production, it is not present long enough in the cell to show any function.

Explanation / Answer

Alanine has propensity to alpha helices nonetheless can also occur in beta sheets and it's usually the same as just truncating side chain back for the beta carbon, the initially side chain atom. The beta carbon position depends on backbone dihedral angles of the polypeptide so is actually section of the main chain structure on the protein. As a result, alanine is usually an acknowledged single residue remains initially selection for mutational scanning because that continues a beta carbon but no other side chain chemistry. Glycine which eliminates a beta carbon is abnormally bendable and will carry out polypeptide backbone conformations usually prohibited simply by various other amino acids, so mutation to glycine will cause flexibility and feasible conformational changes convoluted with the upshots of removing the side chain atoms making interpretation more complicated than for Alanine.

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