PLANT PHYSIOLOGY , Vol 111, Issue 1 215-221, Copyright © 1996 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Purification and Characterization of a Cryoprotective Protein (Cryoprotectin) from the Leaves of Cold-Acclimated Cabbage
F. Sieg, W. Schroder, J. M. Schmitt and D. K. Hincha
Institut fur Pflanzenphysiologie und Mikrobiologie, Freie Universitat, Konigin Luise-Strasse 12-16, D-14195 Berlin, Germany (F.S., J.M.S., D.K.H.)
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.
