BIOC 2580 Study Guide - Midterm Guide: Valence Electron, Glutamine, Hydrogen Bond

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Bioc 2580 fall 2010 midterm: which of the following amino acids has a side chain that contains a carboxylate group at neutral ph, his, asn c. At what ph will the side chain of lys be 20% deprotonated? ( see last page for aa functional group pka values) a. Met arg ala lya gln his asp ser: +0. 5, +1, +1. 5, +2. Bioc 2580 fall 2010 midterm: a mixture of the twenty standard amino acids, dissolved in a buffer with ph=3. 5, is applied to a cation exchange chromatography column. Which amino acids would elute last after applying a buffer containing 1m salt? a. Lys and arg: phe and tyr c. Ser and thr: asp and glu, the relative mobilities of the aa in thin layer chromatography are shown below. Identify the aa that has run 0. 29 m on a large thin layer chromatography plate, when the solvent has run. E: 0. 29 q:0. 63 n:0. 60 f:0. 92 y:0. 82 s:0. 48 a:0. 77.

Related Questions

A mixture of the following peptides is subjected to electrophoresis:

peptide A: lys-trp-arg-asn-met

peptide B: asp-tyr-ala-his-leu

peptide C: ile-glu-gln-cys-val

Calculate the approximate (nearest integer) net charge on each peptide at pH 7. Predict the pattern that would be obtained by subjecting a mixture of the three peptides to electrophoresis at pH 7.(Answer: Peptide A has an approximate charge of +2 at pH 7.)

Please help me with this question,

1. At pH 7.0, in what order would the following three peptides be eluted from a column filled with an anion-exchange polymer? Their amino acid compositions are:

Peptide A: Ala 10%, Glu 5%, Ser 5%, Leu 10%, Arg 10%, His 5%, Ile 10%, Phe 5%, Tyr 5%, Lys 10%, Gly 10%, Pro 5%, and Trp 10%.

Peptide B: Ala 10%, Glu 10%, Gly 5%, Leu 5%, Asp 10%, Arg 5%, Met 5%, Cys 5%, Tyr 5%, Phe 5%, His 5%, Val 5%, Pro 5%, Thr 5%, Ser 5%, Asn 5%, and Gln 5%.

Peptide C: Ala 5%, Val 5%, Gly 10%, Asp 5%, Leu 5%, Arg 5%, Ile 5%, Phe 5%, Tyr 5%, Lys 5%, Trp 5%, Ser 5%, Thr 5%, Glu 5%, Asn 5%, Pro 10%, Met 5%, and Cys 5%.

First off column: _______________ Second: _______________ Last off column: _______________

Consider the peptide:
NH₂-GAPAGPAGTGKTETTKDLAKSMALLCWFNCS-COOH

Table I. pK values of some amino acids

amino acid	pK of side chain or terminal group
Alanine (Ala or A)	uncharged
Arginine (Arg or R)	12.5
Asparagine (Asn or N)	uncharged
Aspartic acid (Asp or D)	3.9
Cysteine (Cys or C)	8.3
Glutamic acid (Glu or E)	4.3
Glycine (Gly or G)	uncharged
Histidine (His or H)	6.0
Leucine (Leu or L)	uncharged
Lysine (Lys or K)	10.8
Phenylalanine (Phe or F)	uncharged
Serine (Ser or S)	uncharged
Tryptophan (Trp or W)	uncharged
Tyrosine (Tyr or Y)	10.9
Valine (Val or V)	uncharged
peptide N terminus	7.8
peptide C terminus	3.6

Using Table I above, determine the net charge of the peptide at pH9.

(the answer is not -1 or 1)

BIOC 2580 Study Guide - Midterm Guide: Valence Electron, Glutamine, Hydrogen Bond

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