Characterization of DHPS from E. coli BN101 and abg derivatives. (a) Comparison of Kms of DHPS from E. coli BN101 (■), BN1001 (•), and BN1004 (○). (b) Comparison of the ability of p-aminobenzoyl-glutamate (p-ABG) to compete with 14C-labeled p-aminobenzoate in the DHPS reaction in E. coli BN101 (•), BN1001 (○), BN1004 (■), and BN1005 (□). p-ABA, p-aminobenzoate; v, velocity.