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Chlorophyll Breakdown in Tobacco: On the Structure of Two Nonfluorescent Chlorophyll Catabolites
Author(s) -
Berghold Joachim,
Eichmüller Christian,
Hörtensteiner Stefan,
Kräutler Bernhard
Publication year - 2004
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200490057
Subject(s) - chemistry , substituent , chlorophyll , moiety , tetrapyrrole , brassica , catabolite repression , protochlorophyllide , conjugated system , enzyme , stereochemistry , biochemistry , botany , organic chemistry , biology , oxidoreductase , gene , mutant , polymer
In extracts of senescent leaves of the tobacco plant Nicotiana rustica , two colorless compounds with UV/VIS characteristics of nonfluorescent chlorophyll catabolites (NCCs) were detected and tentatively identified as Nr ‐NCCs. These two polar NCCs were found in similar amounts in the fresh extracts, and their constitutions could be determined by spectroscopic analysis. The data showed both of the two Nr ‐NCCs to have the same tetrapyrrolic core structure, as reported previously for all other NCCs from senescent higher plants. In the less polar catabolite, named Nr ‐NCC‐2, this core structure was conjugated with a glucopyranose unit, as similarly discovered earlier in Bn ‐NCC‐2, an NCC from oilseed rape ( Brassica napus ). The more polar NCC from tobacco leaves, Nr ‐NCC‐1, carried an additional malonyl substituent at the 6′‐OH group of the glucopyranosyl moiety. Partial (enzyme‐catalyzed) hydrolysis of Nr ‐NCC‐1 gave Nr ‐NCC‐2, while enzyme‐catalyzed malonylation of Nr ‐NCC‐2 gave Nr ‐NCC‐1, establishing the identity of their basic tetrapyrrole structure. In earlier work (on the polar NCCs from oilseed rape), only separate glucopyranosyl and malonyl functionalities were detected. Nr ‐NCC‐1, thus, represents a further variant of the structures of NCCs from senescent higher plants and exhibits an unprecedented peripheral refunctionalization in chlorophyll catabolites.