Treatment of a polypeptide with 2-mercaptoethanol yields two polypeptides 1. Ile—Val—Cys—Arg—Thr—Gly—Cys—Lys—Asn—Phe—Leu 2. Trp—Lys—Cys—Phe—Arg—His—Thr—Lys—Cys—Ser Treatment of the intact polypeptide with trypsin yields fragments with the following amino acid compositions (Arg, Cys2, Ile, Ser, Val) (Arg, Cys2, Gly, Lys, Thr, Phe) (Asn, Leu, Phe) (His, Lys, Thr) (Lys, Trp) Edmands chemistry reveal the following PTH derivatives in equal quantity after cycle 1 • PTH--Ile and PTH--Trp a) Rewrite the intact polypeptide, by indicating the positions of the disulfide bonds (Indicate your reasoning) b) How many products do you expect after chymotrypsin cleavage of the intact polypeptide? c) You are performing an isoelectric focusing experiment (IEF) on a gel with a pH range of 2 to 14. Indicate on the diagram below at what point along the gel will peptide 1 above focus, in the presence (X) and absence (Y) of DTT. (also show your calculations)
Treatment of a polypeptide with 2-mercaptoethanol yields two polypeptides
1. Ile—Val—Cys—Arg—Thr—Gly—Cys—Lys—Asn—Phe—Leu
2. Trp—Lys—Cys—Phe—Arg—His—Thr—Lys—Cys—Ser
Treatment of the intact polypeptide with trypsin yields fragments with the following amino
acid compositions
(Arg, Cys2, Ile, Ser, Val)
(Arg, Cys2, Gly, Lys, Thr, Phe)
(Asn, Leu, Phe)
(His, Lys, Thr)
(Lys, Trp)
Edmands chemistry reveal the following PTH derivatives in equal quantity after cycle 1
• PTH--Ile and PTH--Trp
a) Rewrite the intact polypeptide, by indicating the positions of the disulfide bonds
(Indicate your reasoning)
b) How many products do you expect after chymotrypsin cleavage of the intact
polypeptide?
c) You are performing an isoelectric focusing experiment (IEF) on a gel with a pH range of 2
to 14. Indicate on the diagram below at what point along the gel will peptide 1 above
focus, in the presence (X) and absence (Y) of DTT. (also show your calculations)
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