STUDY OF 650-NM PROTOCHLOROPHYLL FORM IN PUMPKIN SEED COAT

Protochlorophyll forms were investigated by different spectroscopic methods in pumpkin seed coat. The absorption spectrum of the pumpkin seed coat in the red region was similar to the absorption spectrum of etiolated leaves; it showed maxima at 650 and 635 nm. In the fluorescence spectrum there were several bands, which were characteristic of the etiolated leaves. These bands were due to different forms of protochlorophyll and its derivatives. The different protochlorophyll forms in the pumpkin seed coat were inactive upon illumination. On the basis of the changes in absorption spectrum by acetone vapour treatment and of the shape of the circular dichroism (CD) spectrum it can be suggested that the 650 nm protochlorophyll form is a molecular aggregate and that its arrangement is similar to the arrangement obtained in solid film of protochlorophyll. It is not excluded that the 605 nm protochlorophyllide form in etiolated leaves has a similar structure with positive CD signal. © 1979.