In vitro approaches for complex tissue types like muscle, liver, or nerve are still experimental. In vivo synthesis of skin successfully recovers the overall structure of the organ but fails to regenerate organelles such as the sweat glands and hair follicles. These difficulties may be overcome in the future, but currently limit the success of in vivo approaches. Cells bind to various extracellular matrix proteins such as collagen, laminin, fibronectin, and vitronectin through linkages of their integrin receptors with RGD sequences in these proteins. Identify potential interactions of the chemical groups of RGDV shown below that could aid in the binding of integrins to this peptide sequence.
All amide linkages can form hydrogen bonds with other H-bonding groups.
The CH 2 groups of the Arginine side chain may also interact with other chains in this way, but their location near the backbone of the protein will make it difficult for other chains to approach close enough to interact. Provide one possible explanation for the differing degradation rates and, based on your reading, explain one way your hypothesis could be experimentally tested. As we discussed in class, proteins can have order on many levels. The gelatin form of collagen in fact degrades faster than the triple helix form, and the triple helix form degrades faster than the fiber form. Collagens are broken down by protein enzymes in vivo , and the more ordered structures take longer to be broken up by proteolytic enzyme attack.