Proteins from frost-hardy leaves protect thylakoids against mechanical freeze-thaw damage in vitro

✍ Scribed by D. K. Hincha; U. Heber; J. M. Schmitt

• Book ID: 104660279
• Publisher: Springer-Verlag
• Year: 1990
• Tongue: English
• Weight: 386 KB
• Volume: 180
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00198794

✦ Synopsis

We have isolated protein fractions from coldacclimated, frost-hardy cabbage (Brassica oleracea L.) and spinach (Spinacia oleracea L.) leaves which protect isolated thylakoids from non-hardy spinach against mechanical membrane rupture during an in-vitro freezethaw cycle. No protective activity was found in similar preparations from non-hardy leaves. The proteins protected the membranes from damage by reducing their solute permeability during freezing and by increasing their expandability during thawing. The proteins act by increasing the resistance of the membranes against the osmotic stress to which they are exposed during a freezethaw cycle. In the absence of cryoprotectants this stress results in membrane rupture.