Properties of the water-soluble chlorophyll-synthetic linear macromolecular complexes

Abstract

The properties of the water-soluble chlorophyll (Chl) a or b-synthetic linear macromolecular (poly(vinylpyrrolidone)(PVP), poly(ethylene glycol)(PEG) or poly(vinyl alcohol)(PVA)) complexes were investigated. The low-temperature (77 K) fluorescence emission spectra suggested that the Chl a or b-PVP and Chl b-PVA complexes had the similar form of Chl a or b to that of Chl a or b in ethyl ether or Triton X-100, probably a monomeric form, while the Chl a or b-PEG and Chl a-PVA complexes contained the several undefined forms of Chl a or b. The Chl a-PVP complex was eluted at the same volume of the corresponding PVP applied independently to a column of Sephadex G-100, but the Chl a-PEG and Chl a-PVA complexes showed the elution patterns similar to that of Chl a-bovine serum albumin (BSA) complex. The Chls in the synthetic linear macromolecular complexes were stable against oxidative stress of photobleaching, but they were easily hydrolyzed by chlorophyllase, as were the Chls in both the BSA complexes and the isolated light-harvesting Chl a b- protein complex (LHC). A possible localization of Chls within linear macromolecular complexes was suggested so that the tetrapyrrole ring and phytol group of Chl would be surrounded by a linear macromolecular (PVP) chain or a number of linear macromolecular (PEG or PVA) chains, whereas the hydrophyllic edge of porphyrin ring, adjacent to the phytol group, would be exposed to the environment of a water medium.