Answered: 1. Treating (DP) with Flouro Dinitro…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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CASE - 2
On his way back home, MORK from ORK landed on earth after a trip in space to MARS. You were able to
sneak into his space ship and steal a tube labeled decapeptide (DP). Thinking it may be an important
molecule, you started by initially identifying the sequence of the DP.
1. Treating (DP) with Flouro Dinitro benzene (FDNB), followed by hydrolysis resulted in the release of
composing amino acids with none being modified by DNFB. This is because
A. FDNB interacts only with free SH of Cys if present at N or C terminals, suggesting no Cys is present
B. FDNB will interact with the Carboxy -terminal of DP provided it is basic amino acid
C. FDNB modified DP but failed to release the amino acid
D. FDNB could not modify DP suggesting it has no free amino terminal

Transcribed Image Text:Titration of DP with NaOH showed the pH profile presented in curve A (below). DP A. Has one acidic and one basic amino acid B. Has a histidine residue C. Has definitely arginine D. Has one disulfide bridge. ntel ORE IS Gen 3. Treatment of DP with chymotrypsin followed by FDNB released Ala. Titration however of the chymotryspin treated DP showed a pH profile presented in curve B (below). DP definitely has A. His and Glu B. Arg and Lys C. Glutamate at the C-terminal D. A disulfide bridge that was reduced Hd. OHequivalnce 5. 4. Treatment of the DP with chymotrypsin followed by trypsin released the following: - Dipeptide with ala at the N terminal, - Free lys, - A dipeptide with aa that may be labeled using DTNB at its N terminal - A pentapeptide that is cleavable by CNBR yielding: 1) a tripeptide that has 2 leu residues; 2) dipeptide with ala at its N terminal. Assuming that aa composing the DP are: Phe, 2 ala, 2 leu, 2 sulfur containing aa, and 3 basic amino acids, which of the following presents the proper sequence of the DP after chymotrypsin treatment A. phe-ala-cys-lys-arg-arg-met-ala-leu-leu B. ala- lys-cys-lys-his-met-leu-leu -ala-phe C. ala-lys-lys-cys-arg-leu-leu-met-ala-phe D. phe-lys-ala-cys-arg- leu-leu- met-ala-lys 5. The original DP is a A. Dimer of DP linked by electrostatic bridges between the C/N terminals B. Dimer of 2 DP linked by disulfide bridges C. Cyclic peptide Write down HP structure. 2.

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