Proteins I_PS4_F10

Proteins I_PS4_F10 - CHEM 4511/6501 Problem Set 4 1. What...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
CHEM 4511/6501 Problem Set 4 1. What is the approximate molecular weight of a protein with 682 amino acid residues in a single polypeptide chain? 2. A peptide has the following sequence: EHWSGLRPG (A) What is the net charge of the molecule at pH 3, 8, and 11? (B) Estimate the pI for this peptide. 3. One method to separate polypeptides makes use of their different solubilities. The solubility of large polypeptides in water depends on the relative polarity of their R groups, particularly on the number of ionized groups: the more ionized groups there are, the more soluble the peptide. Which of each pair of the polypeptides that follow is more soluble at the indicated pH? (A) (G) 20 or (E) 20 at pH 7.0 (B) (KA) 3 or (FM) 3 at pH 7.0? (C) (ASG) 5 or (NSH) 5 at pH 6.0 (D) (Ala-Asp-Gly) 5 or (Asn-Ser-His) 5 at pH 3.0 5. Which peptide has greater absorbance at 280 nm? (A) Gln-Leu-Glu-Phe-Thr-Leu-Asp-Gly-Tyr (B) Ser-Val-Trp-Asp-Phe-Gly-Tyr-Trp-Ala 6. Protein X has an extinction coefficient of 0.3 mL•mg -1 •cm -1 at 280 nm. What is the absorbance at 280 nm of a 2.3 mg•mL -1 solution of protein X? Assume a path length of 1 cm. 7. Mixtures of amino acids can be analyzed by first separating the mixture into its components through ion-exchange chromatography. Amino acids placed on a cation exchange resin containing sulfonate groups (-SO 3 - ) flow down the column at different rates because of two factors that influence their movement: (1) ionic attraction between the sulfonate residues on the column and positively charged functional groups of the amino acids, and (2) hydrophobic interactions between amino acid side chains and the strongly hydrophobic backbone of the polystyrene resin. For each pair
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/04/2010 for the course CHEM 6501 taught by Professor Wendyl.kelly during the Fall '10 term at Georgia Tech.

Page1 / 3

Proteins I_PS4_F10 - CHEM 4511/6501 Problem Set 4 1. What...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online