Changes in the near-UV fluorescence excitation spectrum during protochlorophyllide photoreduction in etiolated cucumber cotyledons

Title:

Changes in the near-UV fluorescence excitation spectrum during protochlorophyllide photoreduction in etiolated cucumber cotyledons

Creator:

Durchan, M. and Lebedev, N.

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:1d0c3537-ebbb-4046-87a7-29dcc4e109f3
uuid:1d0c3537-ebbb-4046-87a7-29dcc4e109f3
urnnbn:urn:nbn:cz:aba007-000fpi

Subject:

Cucumis sativus L., energy transfer, protochlorophyllide reductase, and Shibata shift

Type:

model:internalpart and TEXT

Format:

print

Description:

Fluorescence excitation spectra of different protochlorophyll(ide) (PChlide) a forms in intact etiolated cucumber cotyledons showed a pronounced increase in intensity of the 390 nm band in comparison with spectra of the pigment in Solutions. The native PChlide F657 also had an additional band at 360 nm in its excitation spectra, which disappeared after leaf homogenization and was restored by addition of dithionite. The restoration correlated with changes around 340 nm in the excitation spectrum of blue-green fluorescence. In consideration of this fact, the 360 nm band seems to correspond to energy transfer from NADPH to PChlide a. After the onset of irradiation a new band appeared at 380 nm in the excitation spectrum of the main pigment fluorescence, which was very similar to that found in the absorption spectinm of isolated Chl a. Moreover, in the Soret region the excitation spectrum had a double band splitting which disappeared only after the Shibata shift, simultaneously with the disappearance of the 360 nm band. Besides the well-known PChl(ide) F633, F642, and F657 forms, etiolated cucumber cotyledons háve emission at 673 nm. Its excitation spectrum was hardly distinguishable from the PChlide F657 fluorescence excitation spectrum in etiolated samples. In the irradiated plants this band had excitation spectrum of monomeric Chl a. The intensity of band at 673 run decreased and transiently increased after PChlide photoconversion. The dynamics of these fluorescence intensity changes under inadiation showed positive correlation both with PChlide F657 and with PChl(ide) F642, indicating the short wavelength Chl a preexistence in etiolated plants and its additional formation after the onset of irradiation.

Language:

Multiple languages

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Coverage:

599-611 and 121-133

Source:

Photosynthetica | 1995 Volume:31 | Number:4

Harvested from:

CDK

Metadata only:

false