Question

S V R

c) What is the overall charge of the most abundant tripeptide species at neutral pH (pH 7.0)?

e) What is the overall charge of the most abundant tripeptide species below pH 1.0?

f) What is the overall charge of the most abundant tripeptide species at pH 11.5?

b) What are the three-letter abbreviations for the amino acids? S: Ser Arg Val V: R: c) What is the overall charge of the most abundant tripeptide species at neutral pH (pH 7.0)? Number Enter your answer as a whole number d) At physiological pH, what is the best description of the chemical properties of the side chain (R group)? positively charged hydrophobic R: S: polar, uncharged V: continued below... e) What is the overall charge of the most abundant tripeptide species below pH 1.0? Number Enter your answer as a whole number. f)What is the overall charge of the most abundant tripeptide species at pH 11.5? Number Enter your answer as a whole number.

Answer 1

amino acids	At pH 7	At pH 1.0	At pH 11.5
N-terminal (pKa = 9.15)	+1	+1	0
S	0	0	0
V	0	0	0
R(side chain pKa = 12.48)	+1	+1	+1
C- terminal (2.17)	-1	0	-1
Net charge	+1	+2	0

Rule for N- Terminal end

when pH < pKa, charge assign = +1

pH > pKa, charge assign = 0

Rule for positively charged side group(Arg, Lys, and His)

pH < pKa, charge assign = +1

pH > pKa, charge assign = 0

Rules for negatively charged side group(Asp and Glu) and C- terminal end

when pH < pKa, charge assign = 0

pH > pKa, charge assign = -1