The amino acids Gly and Pro, as well as modified prolines th…
The amino acids Gly and Pro, as well as modified prolines that have a hydroxyl group on the Pro ring or Hyp, are the principal amino acids comprising collagen. Consider this excerpt from this article: Beck, K., Chan, V. C., Shenoy, N., Kirkpatrick, A., Ramshaw, J. A. M., & Brodsky, B. (2000). Destabilization of osteogenesis imperfecta collagen-like model peptides correlates with the identity of the residue replacing glycine. Proc. Natl. Acad. Sci. U.S.A. 97 (8) 4273–4278. “Gly-Pro-Hyp is the most common, as well as the most stabilizing, triplet in collagen (5). The presence of Gly at every third residue is considered essential….” If there is a genetic mutation that interrupts this pattern of Gly at every third position, bones do not develop properly. They are characteristically brittle, resulting in a genetic disease known as osteogenesis imperfecta. Use your knowledge of the structure of collagen to explain why this regularly repeating Gly residue is essential to the formation of a proper and strong collagen triple helix. (2 pts.) Vitamin C is required for the biochemical reaction that puts the modifying OH group on a Pro in collagen. Why does a vitamin C deficiency result in changing the overall strength of collagen? (2 pts.)
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