N-Acetylglutamic acid is an important regulatory molecule for the urea cycle. Assuming that N-acetylation of the amino group has no effect on the pKa values for the carboxylates, what is the pI for the N-acetylglutamate. For glutamic acid, pKa-COOH = 2.19, pKa-amino group = 9.67, and pKR = 4.25. A. pI < 1.2 B. pI = 3.2 C. pI = 5.9 D. pI = 7.0 E. pI = 9.7