At physiological pH, what is the approximate net charge of a hexapeptide with the following amino acid sequence?
Asp-Val-Ile-Glu-Arg-Ser
A) -2
B) -1
C) 0
D) +1
E) +2

Question

At physiological pH, what is the approximate net charge of a hexapeptide with the following amino acid sequence? 
Asp-Val-Ile-Glu-Arg-Ser
A) -2
B) -1
C) 0
D) +1
E) +2

Quizplus · Accepted Answer

Each of the acidic amino acids Asp (aspartic acid) and Glu (glutamic acid) carries one negative charge on its side chain at neutral pH, while Arg (arginine) carries one positive charge. The side chains of the other residues shown are not ionized at neutral pH. Additionally, the terminal amine group (one positive charge) and carboxyl group (one negative charge) neutralize each other.

At Physiological PH, What Is the Approximate Net Charge of a Hexapeptide