The scientists propose polyproline, a polypeptide made only from the natural amino acid proline, as a versatile alternative cryoprotectant. (sciencedaily.com)
However, after Anthony insisted that it could happen, I looked into the matter more deeply, and that was when I realized that the coding amino acid proline also has a carbon substitution for the hydrogen atom normally attached to the nitrogen atom, but has no trouble linking up with the other amino acids. (westonaprice.org)
Moreover, the free amino acid proline, the building block of polyproline, serves as a natural cryoprotectant on its own; plant cells overproduce proline to keep their osmotic balance and protect themselves from dehydration. (sciencedaily.com)