Cooperativity in Enzyme-Substrate Complex Formation in Nitrogenase-like Dark Operative Protochlorophyllide Oxidoreductase (DPOR)

Giada Bedendi; Plinio Maroni; Ross D. Milton

doi:10.2533/chimia.2026.327

Cooperativity in Enzyme-Substrate Complex Formation in Nitrogenase-like Dark Operative Protochlorophyllide Oxidoreductase (DPOR)

Authors

Giada Bedendi Department of Inorganic and Analytical Chemistry, University of Geneva, Geneva, CH-1205, Switzerland
Plinio Maroni Department of Inorganic and Analytical Chemistry, University of Geneva, Geneva, CH-1205, Switzerland
Ross D. Milton Department of Inorganic and Analytical Chemistry, University of Geneva, Geneva, CH-1205, Switzerland

DOI:

https://doi.org/10.2533/chimia.2026.327

Keywords:

Cooperativity, DPOR, Kinetics, Nitrogenase

Abstract

Dark-operative protochlorophyllide oxidoreductase (DPOR) performs the stereoselective two-electron reduction of protochlorophyllide to chlorophyllide. Importantly, like nitrogenase, DPOR has two functional and coupled substrate reduction sites. DPOR also permits the relatively rare formation of the enzyme-substrate complex to be followed in real-time. We report that substrate binding, prior to its reduction, is a cooperative process.