#Question id: 174
#Unit 1. Structure and Function of Biomolecules
What is the net charge on the dipeptide Arg-Pro at pH 9.0? The table below gives the pKaʹs of the ionizable groups on the free amino acids.
#Question id: 175
#Unit 1. Structure and Function of Biomolecules
The ionic charges associated with a protein molecule are ________.
#Question id: 176
#Unit 1. Structure and Function of Biomolecules
A peptide has the sequence Glu–His–Trp–Ser–Gly–Leu–Arg–Pro–Gly. What is the net charge of the molecule at pH 3
#Question id: 177
#Unit 1. Structure and Function of Biomolecules
The titration curve of alanine shows the ionization of two functional groups with pKa values of 2.34 and 9.69, corresponding to the ionization of the carboxyl and the protonated amino groups, respectively. The titration of di-, tri-, and larger oligopeptides of alanine also shows the ionization of only two functional groups, although the experimental pKa values are different. The trend in pKa values is summarized in the table. Which of the following is a reason for this shift in pK values
#Question id: 178
#Unit 1. Structure and Function of Biomolecules
Given the pKa values of different acidic sites in cysteine, the principal ionic form which will never exist at any pH
#Question id: 179
#Unit 1. Structure and Function of Biomolecules
The average molecular weight of the 20 standard amino acids is 138, but biochemists use 110 when estimating the number of amino acids in a protein of known molecular weight. Why?