BIOCHEMISTRY - L. Stryer - 1984

VOLUME 1

PART I. CONFORMATION AND DYNAMICS

CHAPTER 9. CONNECTIVE TISSUE PROTEINS: COLLAGEN, ELASTIN, AND PROTEOGLYCANS

QUESTIONS AND PROBLEMS

1. The chemically synthesized polypeptide poly-L-Proline folds into a helix similar to each of the individual strands in the Collagen triple helix.

a) Poly-L-proline is unable to form a triple helix. Why?

b) Poly(Gly-Pro-Pro) forms a triple helix similar to that of collagen. Predict the thermal stability of poly(Gly-Pro-Gly) triple helices compared to poly(Gly-Pro-Pro).

c) Can poly(Gly-Pro-Gly-Pro) form a triple helix similar to collagen?

2. Consider the following Amino Acid Sequence: -Gly-Leu-Pro-Gly-Pro-Pro-Gly-Ala-Pro-Gly-.

a) Which of The amino acid residues can be hydroxylated at C-4 by prolyl hydroxylase?

b) Which of the peptide bonds should be most susceptible to Cleavage by Clostridium histolyticum collagenase?

3. Several types of covalent cross-links in Proteins were discussed in this chapter. Are there covalent cross-links in the following proteins? If so, what kind of links are they: a) Ribonuclease; b) Hemoglobin; c) fibrin; d) collagen; e) Elastin?

4. In the absence of one of its substrates, peptidyl proline, prolyl hydroxylase can decarboxylate α-ketoglutarate. This reaction requires reduced iron, O2, and ascorbic acid. Based on this fact, what Conclusion can be drawn about the enzymatic mechanism of the hydroxylation reaction?



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