[Characteristics of photosystem I from grana thylakoids and from stroma lamellae].

Photochemical and spectral properties of photosystem I particles isolated from grana thylakoids and stroma lamellae of chloroplasts of higher plants are studied. The similarity of P700 content in these particles and the same dependence of P700+ reduction on temperature and the time course of variable fluorescence from artificial electron donors and acceptors indicate on the same type of reaction center for both photosystems I. Stroma particles have a higher rate of dark relaxation of variable fluorescence and a higher rate of dark reduction of P700+ at room temperature, than grana particles. Moreover, on the basis of data on low temperature fluorescence spectra, the stroma particles contain less shortwave chlorophyll a forms than grana particles. Thus, photosystem I from grana thylakoids and from stroma lamellae have the same type of reaction centers and can differ only by their nearest environment.