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 hydroxy group on the Pro ring or Hyp, are the principal amino acids comprising collagen. Consider this excerpt from this article: Destabilization of osteogenesis imperfecta collagen-like model peptides correlates with the identity of the residue replacing glycineKonrad Beck, Virginia C. Chan, Nigel Shenoy, Alan Kirkpatrick, John A. M. Ramshaw, and Barbara BrodskyPNAS April 11, 2000 97 (8) 4273-4278; https://doi.org/10.1073/pnas.070050097 “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.)

Questions 2–9 refer to this toxic peptide. General Instructi…

Questions 2–9 refer to this toxic peptide. General Instructions: If the question does not require you to draw a structure, you may answer using either the full name of an amino acid or use its three-letter or single-letter code.   Many animal toxins are peptides. One of these is a 42-residue toxic peptide found in the South American rattlesnake, Crotalus durissus terrifics. The primary sequence of this peptide is shown below and its structure is shown in the figure. YKQCHKKGGHCFPKEKICLPPSSDFGKMDCRWRWKCCKKGSG Image Description  A 3D protein structure showing the positions of cysteine residues (Cys4, Cys11, Cys18, Cys30, Cys36, and Cys37) highlighted in yellow. The protein has an N-terminal (N) and C-terminal (C) with distinct secondary structures: alpha-helices in red and beta-sheets in blue, connected by green loops. The cysteine residues form disulfide bonds, contributing to the protein’s stability and shape.