Lehninger AL, et al., 1993

Nelson and Cox report a nearly complete set of pK values in their first rewrite of Lehninger's classic biochemistry text book, Principles of Biochemistry (1993) (1). The pK values are for the free amino acids in solution, as that is the area in which they are introduced, and these values are applied to problems relating to the free amino acids. These pK values remain unchanged through subsequent editions of Principles of Biochemistry.

Amino acid pK values from Lehninger AL, Nelson DL & Cox MM, 1993 (1).

Group

2.16

†‡

ASP

3.65

†

GLU

4.25

†

HIS

6.00

†

9.47

†¶

CYS

8.18

†§

TYR

10.07

†

LYS

10.53

†

ARG

12.48

†

† Data from Table 5-1.

‡ This value is derived from these data by determining the mean value of the carboxylic acid pK values for the twenty amino acids.

¶ This value is derived from these data by determining the mean value of the amino group pK values for the twenty amino acids.

§ Note that the pK values of the sidechain sulfhydryl group and the amino group of cysteine are reversed in Table 5-1 of the second edtion of the text. The pK values are correct in the third and subsequent edtions of the text.