OldExamV1 - _ Name and ID# (usually your SOLAR Number)...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
_________________________________________________ Name and ID# (usually your SOLAR Number) 11.-4. For each of the following pairs of amino acids or peptides, indicate which will emerge FIRST from a column of the specified solid phase support, using the specified elution solvent: 1. ALA and PHE from a column of unmodified polystyrene beads, eluted with pH 7 aqueous buffer. A. ALA B. PHE C. both emerge simultaneously D. neither can be eluted 2. GLU and HIS from a column of amine-modified polystyrene beads, eluted with an aqueous buffer of progressively decreasing pH. A. GLU B. HIS C. both emerge simultaneously D. neither can be eluted 3. GLU-VAL and ASP-GLY from a column of amine-modified cellulose, eluted with a butanol-acetic acid-water buffer of progressively decreasing pH A. GLU-VAL B. ASP-GLY C. both emerge simultaneously D. neither can be eluted 4. GLU and ALA-ASP-VAL from a column of sulfonic acid-modified polystyrene, eluted with an aqueous buffer of progressively increasing pH. A. GLU B. ALA-ASP-VAL C. both emerge simultaneously D. neither can be eluted For the next questions, remember that when amino acids in a peptide are listed with commas between them (e.g. W,X,Y,Z) the sequence is not specified, but when they are listed with dashes between them the sequence is listed from the amino-terminal to the C-terminal end (e.g. W-X-Y-Z). 5. A hexapeptide has amino acid composition (ALA,ASP,GLU,GLY,MET,LYS). If the peptide is treated with boiling 6 N HCl for 24 hours and the reaction mixture is then titrated fully with NaOH, how many equivalents of base are consumed per mole of starting hexapeptide? A. 2 B. 6 C. 12 D. 14 E. 18 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
_________________________________________________ ______________________ Name and ID# (usually your SOLAR Number) School (Med, Dent, Grad) 6.-8. The same starting hexapeptide (ALA,ASP,GLU,GLY,MET,LYS) is instead treated with cyanogen bromide, yielding two tripeptides, one of which contains homoserine lactone. Another aliquot of the same hexapeptide is digested with trypsin, yielding a lysine-containing dipeptide and a tetrapeptide not containing lysine. If yet another aliquot of the same starting hexapeptide is treated with dansyl chloride and then with 6 N HCl for 24 hours, DNS-GLY is found. 6. The pI of the starting hexapeptide is: A. N3 (between 2.5 and 4.5) B. 4.5 C. N7 (between 4.5 and 10) D. 10 E. N14 (above 12) 7. The pI of the tetrapeptide released after tryptic digestion is: A. N3 (between 2.5 and 4.5) B. 4.5 C. N7 (between 4.5 and 10) D. 10 E. N14 (above 12) 8. If the mixture of products from tryptic digestion of the hexapeptide is reacted with dansyl chloride without further fractionation and then treated with boiling 6N HCl prior to analysis: A. N,N-diDNS-Lys can be detected B. DNS-Gly and one other DNS-amino acid which can’t be predicted are found. C. A dansylated dipeptide and a dansylated tetrapeptide are found.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 9

OldExamV1 - _ Name and ID# (usually your SOLAR Number)...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online