4. The sequence of a peptide A formed by 16 amino acids was determined using a combination of methods that included the use of the Sanger's reagent, protease treatment and SDSPAGE/2D-electropheresis. The following data was obtained from the mentioned experiments: (a) Treatment of peptide A with an excess of fluoro-2,4-dinitrobenzene followed by peptide digestion with concentrated HI and analysis of the hydrolysate showed the presence of 2,4-dinitroderivatives of Ala and Glu. (b)Treatment of the same peptide with carboxypeptidase A resulted in free Tyr and free Ala. (c) SDS-PAGE of peptide A showed only one band at a molar mass of 18 kDa. After treatment with ß-mercaptoethanol and a second electrophoresis trial, one band appeared on the gel but this time the molar mass of the band was approximately 900 Da. Isoelectric focusing of the peptide isolated from this band resulted in two separate bands at pl 9.8 and 4.5 (d) After treatment of peptide A with beta-mercaptoethanol and carboxymethylation by iodoacetate the two peptides were separated by ion-exchange chromatography and each peptide A and B was treated with proteases. ()Treatment of peptide A with trypsin resulted in the following fragments: Ala-Val-Lys, Cys-Tyr and Leu-Phe-Arg ()Treatment of peptide B with trypsin resulted in a large fragment containing the sequence: Val-Trp-Gly-Cys-Ala and a shorter peptide Glu-Met-Lys. Use these data to solve the structure of this peptide. Show the possible location of the disulfide bridge
2.
4. The sequence of a peptide A formed by 16 amino acids was determined using a combination of methods that included the use of the Sanger's reagent, protease treatment and SDSPAGE/2D-electropheresis. The following data was obtained from the mentioned experiments:
(a) Treatment of peptide A with an excess of fluoro-2,4-dinitrobenzene followed by peptide digestion with concentrated HI and analysis of the hydrolysate showed the presence of 2,4-dinitroderivatives of Ala and Glu.
(b)Treatment of the same peptide with carboxypeptidase A resulted in free Tyr and free Ala.
(c) SDS-PAGE of peptide A showed only one band at a molar mass of 18 kDa. After treatment with ß-mercaptoethanol and a second electrophoresis trial, one band appeared on the gel but this time the molar mass of the band was approximately 900 Da. Isoelectric focusing of the peptide isolated from this band resulted in two separate bands at pl 9.8 and 4.5
(d) After treatment of peptide A with beta-mercaptoethanol and carboxymethylation by iodoacetate the two peptides were separated by ion-exchange chromatography and each peptide A and B was treated with proteases. ()Treatment of peptide A with trypsin resulted in the following fragments: Ala-Val-Lys, Cys-Tyr and Leu-Phe-Arg ()Treatment of peptide B with trypsin resulted in a large fragment containing the sequence: Val-Trp-Gly-Cys-Ala and a shorter peptide Glu-Met-Lys. Use these data to solve the structure of this peptide. Show the possible location of the disulfide bridge
Trending now
This is a popular solution!
Step by step
Solved in 3 steps
