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AGREGATION DES CHLOROPHYLLES IN VITRO ‐II. PHOTODECOLORATION DE LA CHLOROPHYLLE a ADSORBEE SUR DES PARTICULES DE LIPOPROTEINES EXTRAITES DU LAIT
Author(s) -
DINANT M.,
AGHION J.
Publication year - 1973
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1973.tb06327.x
Subject(s) - molar absorptivity , chemistry , absorption (acoustics) , adsorption , analytical chemistry (journal) , chromatography , materials science , optics , physics , composite material
— Chlorophyll a (chl a ) adsorbed on milk proteins or lipoproteins has absorption maxima at 437 ± 1 nm and 671 ± 1 nm, whatever its concentration. A 750‐nm‐absorbing form appears when (chl/proteins) > 2 × 10 ‐2 mg chl/mg proteins, in the case of lipoproteins; or 4.5 × 10 ‐3 mg chl/mg proteins, in the case of proteins. In both cases, the apparent molar extinction coefficient at 671 nm is the same (3 × 10 4 liter mole ‐1 cm ‐1 ) at the highest (chl/proteins) ratio for which no 750 nm absorbancy appears. It is shown that adsorbed chl a undergoes irreversible (in the present conditions) photo‐oxidation by light in the presence of oxygen. The reaction is second order, with similar rate constants for chl a adsorbed to proteins or to lipoproteins.