Table 3.

Contributions of EcGK amino acids 423–436 to IIA^Glc inhibition of chimeric enzyme H^II:E423–442

Amino acid substitution in HII:E423–442	vi/vo
None	0.50
S423A	0.50
G427D	1.12
T428V	0.38
R429N	0.22
E434V	0.52
R436K	0.46

Glycerol kinase activity in crude cellular extracts was determined in duplicate without and with 10 μM IIA^Glc added to the assay and corrected for glycerol-independent background rates. IIA^Glc inhibition is expressed as the ratio of the reaction velocity with IIA^Glc, v_i, to the velocity without IIA^Glc, v_o. Duplicate values for v_i/v_o differed from the reported average value by 0.01 or less.

^*Amino acid substitutions in this chimeric enzyme are shown by using the single-letter abbreviations and sequence number, where the amino acid replacement is the residue in HiGK.

^† Determination of the IIA^Glc concentration dependence of inhibition for the H^II:E423–442 parent enzyme yielded K₅₀ = 3 ± 0.2 μM and I_max = 65 ± 1%.