W. Muhlecker et al., Breakdown of chlorophyll: A fluorescent chlorophyll catabolite from sweet pepper (Capsicum annuum), HELV CHIM A, 83(1), 2000, pp. 278-286
The primary fluorescent chlorophyll catabolite 1(Ca-FCC-2) from sweet peppe
r (Capsicum annuum) has similar optical properties, but is slightly less po
lar than the primary FCC (pFCC; 2) from senescent cotyledons of oilseed rap
e (Brassica napus). Ca-FCC-2 was prepared from pheophorbide a using an enzy
me extract from ripe C. annuum chromoplasts. The catabolite Ca-FCC-2 (1) co
uld be determined from fast-atom-bombardment (FAB) mass spectra to be an is
omer of pFCC (2). The constitution of Ca-FCC-2 was determined by homo- and
heteronuclear magnetic-resonance experiments and was found to be identical
to that of pFCC. Further 2D-homonuclear spectra of Ca-FCC-2 revealed it to
differ from pFCC by the configuration at the methine atom C(lj, whose confi
guration results from the action of red chlorophyll catabolite reductase (R
CCR). The occurrence of two primary FCCs that are epimeric at C(1) provides
a structural basis for the recent observation of two types of RCCRs among
higher plants.