Question

Keratin and silk proteins are strengthened by which of the following: a. Beta pleated sheets. b. Alpha helices c. Greek keys d. Methylation groups

Answer 1

Option a is the correct answer.

keratin and silk proteins are strengthened by Beta-pleated sheets. The beta pleated sheet of silk is connected by hydrogen bonds. The hydrogen bonds in the silk form beta pleated sheets rather than alpha helixes because of where the bonds occur. The hydrogen bonds go from the amide hydrogens on one protein chain to the corresponding carbonyl oxygen across the way on the other protein chain. This is in contrast to the alpha helix because in that structure the bonds go from the amide to the carbonyl oxygen, but they are not adjacent. The carbonyl oxygen is on the amino acid that is four residues before. The formation of the secondary protein structure in silk allows it to have very strong tensile strength.