Keratins are a family of tough and insoluble proteins that are able to form fibe

Question

Keratins are a family of tough and insoluble proteins that are able to form fibers. They form the hard but unmineralized (not bony) structures in amphibians, mammals and reptiles/birds. Keratin, a byproduct from the poultry industry, has recently sparked interest. Keratines are made from a high proportion of the amino acid glycine (R=H), followed by the amino acid alanine (R=-CH3). Two neighboring strands of keratine are shown below. To what class of polymers is Keratine quite similar?

A. Polyesters such as PET

B. polyamides, such as nylon

D. polyurethanes

A. Polyesters such as PET

B. polyamides, such as nylon

C. polyalkenes, such as polyacrylate

D. polyurethanes

RO RO RO RO H-CHO NH RH 0-NHRHO-NHRH0 N-CH-C-NH-CH-C-NH-CH-C-NH-CH-C n O N-CH-C-NH-CH-C-NH-CH-C-NH-CH-C n OIC C-R OIC CIR OIC CIR HN HN

Explanation / Answer

During formation of Keratine protein, N atom of one amino acid (glycine) reacts and binds to the C atom of the other amino acid (alanine). Therefore, Keratine is a polyamide.

The correct answer is (B) polyamides, such as nylon.

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