Question

which of the following statements about the charge distribution on the amino acid glutamate is incorrect ?

glutamate has three different ionizable groups

at a very low pH, the most abundant form of glutamate will have net charge of +1

at a very high pH the most abundant form of glutamate will have a net charge of -2

at a pH of aprox. 3.2 glutamate will not contain any charged groups

all of the above are correct

Answer 1

Ans. Statements C and D are incorrect.

Incorrect statement C = At pH of approx.. 3.2 glutamate will not contain any charged groups. At this pH, the N-terminal amine group has a +0.99 (=+1.0 approx.) unit charge, the C-terminal carboxyl group has (-) 0.91 unit charge. So, this statement is incorrect.

D = All of the above statements are correct. Statement C is incorrect.

# Glutamate has three ionizable groups- the N-terminal amine group, the C-terminal carboxyl group, and the R-group.

# As calculated-

            At very low pH, say 1.00, it has a net charge of +1.

            At very low pH, say 14.00, it has a net charge of -2.

So, statements A, B and C are true.