Question

Styles A decapeptide has the following amina acid composition: Arg. Asp, Gly, Leu, Lys, Met, Phe, Ser. Trp, and Val Reacting the native peptide with FDNB and then hydrolyzing released 2.4- dinitrophenylvaline. Brief incubation of the native peptide with carboxypeptidase yielded free Leu. Incubation with cyanogen bromide yielded two fragments: a tetrapeptide with composition Met, Phe, Ser, and Val, and a hexapeptide. The hexapeptide yielded 2.4- dinitrophenylglycine. Proteolytic cleavage by trypsin of the native peptide gave free Leu, a tripeptide, and a hexapeptide. The tripeptide revealed Asp. Arg. and Trp. Chymotrypsin cleavage revealed a dipeptide, a tripeptide and a pentapeptide. The dipeptide revealed Phe and Val. The tripeptide yielded 2,4-dinitrophenylaspartic acid. The pentapeptide revealed 2,4-dinitrophenylserine. Draw the sequence of the native polypeptide.

Answer 1

Styles A decapeptide has the following amino acid composition: Arg, Asp, Gly, Leu, Lys, Met, Phe, Ser. Trp, and Val Reacting the native peptide with FDNB and then hydrolyzing released 2,4- dinitrophenylvaline. G at 'N'-terminal at 'c'terminale 6. Brief incubation of the native peptide with carboxypeptidase yielded free Leu. Incubation with cyanogen bromide yielded two fragments: a tetrapeptide with composition Met, Phe, Ser, and Val, and a hexapeptide. The hexapeptide yielded 2.4- dinitrophenylglycine. Proteolytic cleavage by trypsin of the native peptide gave free Leu, a tripeptide, and a hexapeptide. The tripeptide revealed Asp. Arg. and Trp. Chymotrypsin cleavage revealed a dipeptide, a tripeptide and a pentapeptide. The dipeptide revealed Phe and Val. The tripeptide yielded 2,4-dinitrophenylaspartic acid. The pentapeptide revealed 2,4-dinitrophenylserine. Draw the sequence of the native polypeptide. Analysing first * hint * 2.4 DNF B C2,4 dinitro fluorobenzene) is a sanger's Reagent and this interact with acid present at 'N' - terminus of polypeptide i.e. Amino acid with free amino \\Н, So, as 1 hint suggests, after Reaction with 2,4 - DNFB, the product is dinitrophenylvaline to meaning valine has interacted with 2,4. DN FB thus valine is present at 'N'-terminal. So, Valine has free NH₂ group. * Analysing second hint + Carboxypeptidase cleave's off the first peptide ''-terminal end of Polypeptide. or amide bond at the Carboxyl or Here, it suggest leucine has been separated thus leucine is at 'c' terminal

Styles A decapeptide has the following amino acid composition: Arg, Asp, Gly, Leu, Lys, Met, Phe, Ser. Trp, and Val Reacting the native peptide with FDNB and then hydrolyzing released 2,4- dinitrophenylvaline. Brief incubation of the native peptide with carboxypeptidase yielded free Leu. Incubation with cyanogen bromide yielded two fragments: a tetrapeptide with composition Met, Phe, Ser, and Val, and a hexapeptide. The hexapeptide yielded 2.4- dinitrophenylglycine. S end 'N'end 'N'ende Proteolytic cleavage by trypsin of the native peptide gave free Leu, a tripeptide, and a hexapeptide. The tripeptide revealed Asp. Arg. and Trp. Glycine Chymotrypsin cleavage revealed a dipeptide, a tripeptide and a pentapeptide. The dipeptide revealed Phe and Val. The tripeptide yielded 2,4-dinitrophenylaspartic acid. The pentapeptide revealed 2,4-dinitrophenylserine. Draw the sequence of the native polypeptide. * hint Analysing Third Cyanogen Bromide * hydroluses peptide bonds at 'c' terminal of methionine amino acid Ci.e. cleave through carboxylic part) f 'Cleavage' S и Н 1 с N -C - 1 H CH₂ CH2 S-CH₂ we can our Thus, from above 2 hints 'N' terminus Val - 2 - 3 - 4 say decapeptide has -6-7-8-9-'Leu' following feature 5 'ľ terminus 3 (no. simply Represents amino acids) V Hint Tetrapeptide with 'Met Hexapeptide with 2,4-dinitrophenylglycine) S with Sanger's Reagent i.e. Glycine is Carboxy terminal of Tetrapeptide amino terminal 'N' terminal of hexapeptide + Thus, Val - 2-3 - Met – Gly - 6 - 7-8-9 leu After hint 3

Styles A decapeptide has the following amino acid composition: Arg, Asp, Gly, Leu, Lys, Met, Phe, Ser. Trp, and Val Reacting the native peptide with FDNB and then hydrolyzing released 2,4- dinitrophenylvaline. Brief incubation of the native peptide with carboxypeptidase yielded free Leu. Incubation with cyanogen bromide yielded two fragments: a tetrapeptide with composition Met, Phe, Ser, and Val, and a hexapeptide. The hexapeptide yielded 2.44 dinitrophenylglycine. Proteolytic cleavage by trypsin of the native peptide gave free Leu, a tripeptide, and a hexapeptide. The tripeptide revealed Asp, Arg, and Trp. Chymotrypsin cleavage revealed a dipeptide, a tripeptide and a pentapeptide. The dipeptide revealed Phe and Val. The tripeptide yielded 2,4-dinitrophenylaspartic acid. The pentapeptide revealed 2,4-dinitrophenylserine. Draw the sequence of the native polypeptide. * Analysing fourth hint cleaves the peptide bond mainly at carboxyl side of the Lysine OY Trypsin arginine, So, hint says Decapeptide Trypsin Leucine + Tripeptide + Hexapeptide Containó is of interest Asp, Arg} & Trp So, structure is 'N' terminal Val- 2-3 Met- Gly - 6 - 7 - 8 9 Trypsin Leu $ '' terminal must be must be asp & Trp Arginine (can be in order) * Tryptophane (Trp) is cleaved by Chymotrypsin any so last hint man help.

Styles A decapeptide has the following amino acid composition: Arg, Asp, Gly, Leu, Lys, Met, Phe, Ser. Trp, and Val Reacting the native peptide with FDNB and then hydrolyzing released 2,4- dinitrophenylvaline. Brief incubation of the native peptide with carboxypeptidase yielded free Leu. Incubation with cyanogen bromide yielded two fragments: a tetrapeptide with composition Met, Phe, Ser, and Val, and a hexapeptide. The hexapeptide yielded 2.4- dinitrophenylglycine. Proteolytic cleavage by trypsin of the native peptide gave free Leu, a tripeptide, and a hexapeptide. The tripeptide revealed Asp, Arg. and Trp. Chymotrypsin cleavage revealed a dipeptide, a tripeptide and a pentapeptide. The dipeptide revealed Phe and Val. The tripeptide yielded 2,4-dinitrophenylaspartic acid. The pentapeptide revealed 2,4-dinitrophenylserine. Draw the sequence of the native polypeptide. * * Analysing last hint Chymotrypsin cleaues at 'c' - terminal of aromatic Phenylalanine (Phe), Tryptophan (Trp), Tyrosine (Tyr). amino acids Hint Says → + Val & Phe Decapeptide Chymotrypsin Pentapeptide Dipeptide + Tripeptide 'S with serine at with aspartic 'N' terminal acid at 'N' terminal amino acid after Cafter Rxn with Sanger's Valine Reagent gave 2.4. dinitrophenylaspartic acid 2,4-dinitrophenyl serine as Rx? with Sanger's (Reagent gave Serine is So, 3 5 val - Phen Met- Gly- 4 6 7 - Arg - Leue Chymotrypsin Cleaves here Chymotrypsin cleques here as at 'N' terminal of this pentapeptide [Pentapeptide must be serine Must be aspartic acid Chint no. 3) Cas 'N' terminal of tripeptide is Asp. Tryptophan Chint 4+5 L

final sequence Val- Phe 'N' terminal Ser - Met - Gly- 6 - Trp - Asp - Ang - Leu 'c' terminal A decapeptide has the following amino acid composition: Arg. Asp, Gly, Leu, Lys, Met, Phe Ser, Trp, and Val 6th amino acid is 'Lysine'. * All the hints at once Val Phe Ser-Met & Gly-Lys / Trp {Asp - Ang & Leu S N terminal Chymotrypsin Trypsin Trypsin Cyanogen bromide Chymotrypsin 'C' terminal