Purification and Characterization of a Cryoprotective Protein (Cryoprotectin) from the Leaves of Cold-Acclimated Cabbage.
We have purified a protein (cryoprotectin) from the leaves of cold-acclimated cabbage (Brassica oleracea L.) that protects thylakoids from nonacclimated spinach (Spinacia oleracea L.) against freeze-thaw damage. The procedure involves precipitations by heat, ammonium sulfate, and the glycosaminoglycan heparin and column chromatography on Polyamide 6 and a C18 reverse-phase matrix. After reverse-phase chromatography we obtained a single band of an apparent molecular mass of 7 kD when fractions that showed cryoprotective activity were analyzed by sodium dodecyl sulfate gel electrophoresis and silver staining. Gel-filtration experiments confirmed that the active protein is a monomer of 7 kD native molecular mass. This 7-kD protein could be purified only from cold-acclimated cabbage, but not from plants grown under nonacclimating conditions. Using peroxidase-labeled lectins, we show that cryoprotectin is a glycoprotein and that the saccharide moiety contains [alpha]1-3-linked fucose.
Sieg
F.
F
Institut fur Pflanzenphysiologie und Mikrobiologie, Freie Universitat, Konigin Luise-Strasse 12-16, D-14195 Berlin, Germany (F.S., J.M.S., D.K.H.).
Schroder
W.
W
Schmitt
J. M.
JM
Hincha
D. K.
DK