Organic Chemistry III
	Professor Carl C. Wamser
Chem 336 - Spring Term	Quiz 25

1.  (3 points)  Using only side-chain structures, illustrate specific examples of :

a)  disulfide bridge

b)  H-bonding between Tyr and Asp

c)  Coulombic (charge) attraction between Arg and Glu

2.  (4 points)  Write the complete structure for the tripeptide Met-Phe-Ser, including stereochemistry, as it would appear at pH 7.

You would like to prepare this tripeptide and have available the following bottles:
       M - Met,   P - Phe,   S - Ser,   B - BOC-Cl,   D - DCCI,   H - HBr (aqueous)
Indicate the order in which you would use these to make the desired tripeptide.

3.  (3 points)  Deduce the amino acid sequence of the unknown hexapeptide. 
*  complete hydrolysis releases equal amounts of   Glu, His, Lys, Phe, Ser, Tyr
*  Edman’s reagent releases Ser followed by His
*  chymotrypsin releases Tyr plus a dipeptide and a tripeptide
*  trypsin releases Glu plus a pentapeptide