6. The following polypeptide (30 amino acids) contains a great deal of regular s

Question

6. The following polypeptide (30 amino acids) contains a great deal of regular secondary structure. (10) (15) (20) lys Lys Ala-Phe-Trp-Met-His- GIh-Thr-lle-Arg-Ser-Gly-Ala-Gly-Ser-Gly-Ala-Trp-Tyr-Pro-Val-Ala (30) Phe-Met-Leu-Val-Pro-Glu-Glu There are at least two regions where alpha helical structure is found. Indicate the beginning and ending residues of these regions. Any group or groups which break the alpha helical structure should not be considered part of the helix. Remember that it take four residues to give a turn of an alpha helix, so that is the minimum number of suitable residues necessary to give alpha helical structure. a. b. In which part(s) of the polypeptide would there most likely be beta-pleated sheet structure?

Explanation / Answer

based on standard free energy data for formation of alpha helical structure, it can be concluded that all the value of free energy are calculated with respect to alanine residue. It means the free enrgy value of alanine is taken as zero. So, alanine residue is responsible for breaking of alpha helical structure.

therefore, list of residue for alpha helical are as follow:

first: Phe .....to.....Gly

second: Trp.....to.....Val

b. Large aromatic residues (tyrosine, phenylalanine, tryptophan) and -branched amino acids (threonine, valine, isoleucine) are responsible to form -strands

anser is Phe ....to.....Glu

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