Isolation and characterization of CAC antenna proteins and Photosystem I supercomplex from the cryptophytic alga Rhodomonas salina.

In the present paper, we report an improved method combining sucrose density gradient with ion exchange chromatography for the isolation of pure chlorophyll a/c antenna proteins from the model cryptophytic alga R. salina. Antennas were used for in vitro quenching experiments in the absence of xanthophylls, showing that protein aggregation is a plausible mechanism behind nonphotochemical quenching in R. salina. From sucrose gradient, it was possible to purify also a functional Photosystem I supercomplex, which was in turn characterized by steady-state and time-resolved fluorescence spectroscopy. R. salina Photosystem I showed a remarkably fast photochemical trapping rate, similarly to what recently reported for other red clade algae such as Chromera velia and Phaeodactylum tricornutum. The method reported therefore may be suitable also for other still partially unexplored algae, like cryptophytes. This article is protected by copyright. All rights reserved.