Name (print): 7.Often proteins which perform unrelated functions use strikingly
ID: 132990 • Letter: N
Question
Name (print): 7.Often proteins which perform unrelated functions use strikingly simi accomplish their tasks (eg: beta barrels). We have covered at least 4 different large sca structural patterns or "themes" in this course. Choose one (excluding beta barrels) and briefly describe the overall shape & function and provide two examples of its use in nature appropriate include key differences in the overall shape or structural "theme names and properties (ie: what they do). Figures are not required but may be lar structural patterns to . When " as well as protein helpful. (7 marks) Structural pattern or "theme:" Example 1: Example 2:Explanation / Answer
Shape and function of 2 different structural patterns of proteins. These "theme"s include alpha helix and triple helix.
Example 1: Alpha helix
The peptide chain forms right handed helical coils. These coils are stabilized by hydrogen bonds between the carbonyl-O and the amide-N of different peptide bonds, located on the same peptide chain, but separated from one another by four amino acid residues. The amide-N, the carbonyl-O and the amide-H involved in hydrogen bonding, lie almost along a straight line nearly parallel to the long axis of the helix, While alpha-C, alpha carboxyl carbon and the alpha amino-N of each amino acid residue lie on the backbone of the coil, the sidechains or R groups project radially from the backbone.Each turn of the coil carries 3.6 amino acid residues.
Alpha keratins are abundant in hair, wool, and the stratum corneum of skin.
Example 2: Triple helix
It is a right handed supercoil of three peptide chains called alpha chains. Each alpha chain is in turn coiled into a left handed helix with 3 amino acid residues in each turn of the coil. The structure is stabilized by covalent and noncovalent bonds. These include 1) interchain hydrogen bonds between the carbonyl and amide groups of peptide bonds of different alpha chains 2) interchain aldol cross links, secondary amide bonds and peptide bonds.
Collagen can not form alpha helix because of the presence of helix-destabilizing amino acids like glycine, proline or hydroxyproline. It possesses triple helix.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.