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Updated: Aug 14, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
para-aminobenzoate synthesis from chorismate occurs in two steps
B P Nichols1, A M Seibold, S Z Doktor
1Department of Biological Sciences, University of Illinois, Chicago, 60680.
Abstract:
Escherichia coli p-aminobenzoate synthase is composed of two nonidentical subunits encoded by pabA and pabB and has been assumed to be the sole enzyme responsible for p-aminobenzoate biosynthesis from chorismate and glutamine. Plasmids were constructed that overproduce the p-aminobenzoate synthase subunits 250-500-fold. Partial purification of the subunits revealed that they form a diffusible intermediate that is subsequently converted to p-aminobenzoate by a second enzyme (Mr = 49,000) temporarily designated enzyme X.
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