THE INFLUENCE OF HEAVY METAL IONS ON ABSORPTION SPECTRA OF CHLOROPHYLL FROM <i>EUGLENA GRACILIS (IN VITRO)</i>
Heavy metal environmental pollution is one of the most important ecological problems. Photosyn-thetic organisms are frequently used as test systems, among which the preference is given to microorganisms such as E. gracilis. The changes of physiological characteristics of cells are used as criteria for evaluation of aquatic environmental pollution. At the same time, to understand the essence of physiologic response on the influence of heavy metal ions it is necessary to understand the mechanisms of interactions of pollutant with biochemical systems of a cell. In this research the influence of Fe<sup>2+</sup>, Zn<sup>2+</sup> and Cu<sup>2+</sup> on spectral properties of chlorophyll isolated from E. gracilis culture is studied. The results showed that the mentioned above ions replace Mg<sup>2+</sup> in chlorophyll molecule. This causes the decrease of absorption maxima at 666 nm. The most significant spectral changes were observed when chlorophyll interacted with Fe<sup>2</sup>+, while Cu<sup>2</sup>+ had the least impact. The assumption is given that the values of effective ionic radii and redox potential of pair of Me<sup>2</sup>+/Me<sup>0 </sup>influence the efficiency of interaction of heavy metal ions with molecules of chlorophyll. This interaction can be shown by the changes in absorption spectra of chlorophyll.