Properties of chloroplast membrane-bound ferredoxin--NADP + reductase during cold hardening of wheat. No indication of qualitative membrane changes during cold hardening

Kinetic parameters of the chloroplastbound ferredoxin-NADP⁺ reductase from two varieties of wheat (Triticum aestivum), hardy Kharkov 22 MC (winter wheat) and less hardy Rescue (spring wheat), were followed during induction of frost hardiness as a means of examining possible changes in chloroplast membranes during hardening. No changes were found in the Michaelis constants for NADPH and 2,6-dichlorophenol indophenol, inhibition constants for p-chloromercuriphenylsulfonate, and activation energy values of the enzyme in either variety. The data suggest that no qualitative changes occurred in the properties of wheat chloroplast membranes related to ferredoxin-NADP⁺ reductase during cold hardening.