Upgrade to remove ads
Only $35.99/year

MCB_450_Homework_2

Terms in this set (13)

Phenylalanine
Non-polar
Lysine
Basic
Out of the following amino acid pairs which would have the greatest tendency to be on the interior of a water-soluble globular protein?

a) A and T
b) D and W
c) Q and M
d) A and V
e) K and H
D.
What is the pH of a glycine solution in which the α-NH3+ group is 6/7 dissociated (deprotonated)? The pKa of the α-NH3+ group of glycine is 9.6. Enter your answers using two decimal points.
10.38
Given the following tri-peptide: AGR
Determine the net charge of the peptide at the following three pHs. Use the table of pKa values provided below. Assume you are looking at a single peptide molecule.
pH 13.5
pH 2.5
pH 6.5
pH 13.5: -1
pH 2.5: 2
pH 6.5: 1
Estimate the isoelectric point (pI) for this peptide (enter values with 2 decimal points).
10.2
Given the following sequence of amino acids (from a real protein) having an alpha helix secondary structure:

N'-Ser1-Glu1-Gly1-Asp-Trp-Gln-Leu-Val-Thr-Ile-Arg-Ala-Ser2-Gly2-Glu2-C'

The carbonyl of Leu will be hydrogen bonded to amino group of _________.
Arg
What is the approximate molecular mass (Da) of a protein containing 200 amino acids? (Assume there are no other protein modifications.)

a) 20 Da
b) 20,000 Da
c) 200 Da
d) 22,000 Da
e) None of the above choices are correct.
D.
A common reaction of two cysteine residues in proteins results in the formation of thioester bonds.
False
According to convention, the amino terminus is drawn on the right side of a peptide.
False
A peptide bond is formed between the alpha-carboxyl group of an amino acid and the alpha-amino group of the adjacent amino acid.
True
The zwitterionic species of asparagine predominates in the pH range of 5.0-6.0.
True
Changes in secondary structure create amyloid fibers, which are insoluble and are the source of mad cow disease, and Alzheimer's, and Parkinson's diseases.
True
Sets with similar terms