Partial hydrolysis of a protein yielded a number of polypeptides. One of them was purified. Deduce the sequence of amino acids in this polypeptide from the following information: (a) Complete acid hydrolysis yielded ala + arg + 2ser + lys + phe + met + trp + pro (b) Treatment with fluorodinitrobenzene (FDNB, the Sanger reagent) followed by complete acid hydrolysis yielded dinitrophenylalanine (DNP-ala) and a dinitrophenyllysine (e-DNP-lys) as the only DNP derivatives. (c) Neither carboxypeptidase A nor carboxypeptidase B released a C-terminal amino acid. (d) Treatment with cyanogen bromide (CNBr) yielded two peptides: One contained ser + trp + pro. The other contained all the remaining amino acids (including the second ser). (e) Treatment with chymotrypsin yielded three peptides. One contained only ser + pro. Another contained only met + trp. The third contained phe + lys + ser + arg + ala. (f) Treatment with trypsin yielded three peptides. One contained only ala + arg. Another contained only lys + ser. The third contained phe + trp + met + ser + pro

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Chapter1: Biochemistry: An Evolving Science
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Partial hydrolysis of a protein yielded a number of polypeptides. One of them was purified. Deduce the sequence of amino acids in this polypeptide from the following information:

(a) Complete acid hydrolysis yielded ala + arg + 2ser + lys + phe + met + trp + pro

(b) Treatment with fluorodinitrobenzene (FDNB, the Sanger reagent) followed by complete acid hydrolysis yielded dinitrophenylalanine (DNP-ala) and a dinitrophenyllysine (e-DNP-lys) as the only DNP derivatives.

(c) Neither carboxypeptidase A nor carboxypeptidase B released a C-terminal amino acid.

(d) Treatment with cyanogen bromide (CNBr) yielded two peptides: One contained ser + trp + pro. The other contained all the remaining amino acids (including the second ser).

(e) Treatment with chymotrypsin yielded three peptides. One contained only ser + pro. Another contained only met + trp. The third contained phe + lys + ser + arg + ala.

(f) Treatment with trypsin yielded three peptides. One contained only ala + arg. Another contained only lys + ser. The third contained phe + trp + met + ser + pro

Q1
Partial hydrolysis of a protein yielded a number of polypeptides. One of them was purified. Deduce the sequence
of amino acids in this polypeptide from the following information:
(a) Complete acid hydrolysis yielded ala + arg + 2ser + lys + phe + met + trp + pro
(b) Treatment with fluorodinitrobenzene (FDNB, the Sanger reagent) followed by complete acid hydrolysis
yielded dinitrophenylalanine (DNP-ala) and e-dinitrophenyllysine (e-DNP-lys) as the only DNP derivatives.
(c) Neither carboxypeptidase A nor carboxypeptidase B released a C-terminal amino acid.
(d) Treatment with cyanogen bromide (CNBR) yielded two peptides:
One contained ser + trp + pro. The other contained all the remaining amino acids (including the second ser).
(e) Treatment with chymotrypsin yielded three peptides. One contained only ser + pro. Another contained only
met + trp. The third contained phe + lys + ser + arg + ala.
(f) Treatment with trypsin yielded three peptides. One contained only ala + arg. Another contained only lys +
ser. The third contained phe + trp + met + ser + pro.
Additional Information
• Carboxypeptidase A will cleave at C-terminal amino acids except arginine, lysine, or proline. Carboxyeptidase
B will cleave only C-terminal arginine or lysine. Neither will act on any C-terminal amino acid if the next-to-
last (penultimate) amino acid is proline.
Note. Carboxypeptidases will continue to cleave susceptible C-terminal amino acids. So what we really
determine is the identity of the amino acid that is released most rapidly.
• Cyanogen bromide cleaves specifically on the carboxyl side of methionine residues.
Chymotrpsin cleaves on the carboxyl side of phenylalanine, tyrosine, tryptophan and leucine provided the
next residue (donating the amino group) is not proline.
Trypsin cleaves on the carboxyl side of lysine and arginine provided the next amino acid (donating the amino
group) is not proline.
Transcribed Image Text:Q1 Partial hydrolysis of a protein yielded a number of polypeptides. One of them was purified. Deduce the sequence of amino acids in this polypeptide from the following information: (a) Complete acid hydrolysis yielded ala + arg + 2ser + lys + phe + met + trp + pro (b) Treatment with fluorodinitrobenzene (FDNB, the Sanger reagent) followed by complete acid hydrolysis yielded dinitrophenylalanine (DNP-ala) and e-dinitrophenyllysine (e-DNP-lys) as the only DNP derivatives. (c) Neither carboxypeptidase A nor carboxypeptidase B released a C-terminal amino acid. (d) Treatment with cyanogen bromide (CNBR) yielded two peptides: One contained ser + trp + pro. The other contained all the remaining amino acids (including the second ser). (e) Treatment with chymotrypsin yielded three peptides. One contained only ser + pro. Another contained only met + trp. The third contained phe + lys + ser + arg + ala. (f) Treatment with trypsin yielded three peptides. One contained only ala + arg. Another contained only lys + ser. The third contained phe + trp + met + ser + pro. Additional Information • Carboxypeptidase A will cleave at C-terminal amino acids except arginine, lysine, or proline. Carboxyeptidase B will cleave only C-terminal arginine or lysine. Neither will act on any C-terminal amino acid if the next-to- last (penultimate) amino acid is proline. Note. Carboxypeptidases will continue to cleave susceptible C-terminal amino acids. So what we really determine is the identity of the amino acid that is released most rapidly. • Cyanogen bromide cleaves specifically on the carboxyl side of methionine residues. Chymotrpsin cleaves on the carboxyl side of phenylalanine, tyrosine, tryptophan and leucine provided the next residue (donating the amino group) is not proline. Trypsin cleaves on the carboxyl side of lysine and arginine provided the next amino acid (donating the amino group) is not proline.
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