Glutamate synthesis via photoreduction of NADP(+) by photostable chlorophyllide coupled with polyethylene-glycol

Chlorophyllide a was coupled with alpha-(3-aminopropyl)-omega -methoxypoly( oxyethylene) (PEG-NH2) to form a PEG-chlorophyllide conjugate through an ac id-amide bond. The conjugate catalyzed the reduction of methylviologen in t he presence of 2-mercaptoethanol. It also catalyzed the photoreduction of N ADP(+) or NAD(+) in the presence of ascorbate as an electron donor and ferr edoxin-NADP(+) reductase as the coupling enzyme. Utilizing the reducing pow er of NADPH generated by PEG-chlorophyllide conjugate under illumination, g lutamate was synthesized from 2-oxoglutarate and NH4+ in the presence of gl utamate dehydrogenase. PEG-chlorophyllide conjugate was quite stable toward light illumination compared with chlorophyll a. The increase in the molecu lar weight of PEG in the PEG-chlorophyllide conjugates was accompanied by t he enhancement of photostability of the conjugate and also by the increased solubility in the aqueous solution. (C) 2001 John Wiley & Sons, Inc.