[Molecular arrangement of protochlorophyll aggregated forms in solid films].

The conditions were found for the successive self-assembly of two protochlorophyll aggregated forms in solid films with absorption maxima at 647 (+/-1) nm (PChl 647) and 651 (+/-1) nm (PChl 651) and fluorescence maxima at 653-655 nm and 654-657 nm, respectively. These forms model the native photochemically active form of the precursor of chlorophyll (chlorophyllide) in plants (P650). The investigation of infrared spectra (in the region 1800-1600 cm-1), CD-spectra and fluorescence, carried out in this study, permitted in between the indicated forms to distinguish the type of the molecular arrangement of aggregated structures, PChl 647 is supposed to consist of unstable dimers formed without the participation of keto groups of the cyclopentanone rings, while the structure of PChl 651 includes the dimers to bind more firmly by the intermolecular bonds formed at the expense of keto groups and a central magnesium atom.