Frozen thylakoids: an improvement for reconstituted chloroplast enzyme light-activation systems

This paper describes a new method for improving both the stability and reproducibility of chloroplast enzyme light-activation systems. Usually, the most labile components of these systems are the thylakoids, the preparation of which must be repeated daily. Freezing the thylakoids in small aliquots in liquid nitrogen and storing them at −90°C in a buffer containing 50% glycerol results in preparations whichare completely stable over an 18-month-period. Enzyme light-activation rates were essentially identical with either frozen or fresh thylakoids. Freezing, however, resulted in a slow decline of NADP-protoreduction rates and also in a gradual uncoupling of non-cyclic photophosphorylation.