GRE Subject Question

Matching Nightmare Questions A) Secondary B) Tertiary C) Super-secondary D) Domain I) Final three-dimensional packaging of all three regions of a single polypeptide chain II) Packing together of two or more adjacent folded sections within a contiguous piece of polypeptidechain (found to occur in many unrelated proteins) III) Regular three dimensional folding pattern (repeating pi, psi values) of a contiguous segment of polypeptide chain IV) Binding together and arrangement of separately folded polypeptide chains (subunits) VI) Globular cluster of noncontiguous segments of polypeptide chain to form a unique, identifiable region of protein

interpreting helical wheel projections (alpha helices)

Shows how to interperet a helical projection of an alpha helix: predicting external vs internal side, and determining the amino acid sequence

peptide sequencing

Deducing a peptide sequence from enzymatic and chemical cleavage

re-folding experiments on insulin and pro-insulin

Explains why pro-insulin can be refolded but not insulin (following Anifansen's experiments with ribonuclease)

GRE (Biochem) Subject Question

A major difficulty in investigating the properties of pancreatic serine proteases is that these enzymes, being proteins, are self digesting. The problem however , is less severe for solutions of chymotrypsinthan for solutions of elastase or trypsin. Suggest an explantion for this observation? (Do not consider the zymogen activation steps(Chymotripsinogen to chymotrypsin) but only the final active form of these proteins.