PEG effect in protoplast fusion

Bao Xue bxue at
Tue Dec 21 15:57:03 EST 1993

I read a posting asking for help with the effect of PEG in fusions.  I can't 
find it right now so I'll post an answer seperately instead of a follow-up.

The ether linkages in PEG make the molecule slightly  negative in polarity and 
capable of forming hydrogen bonds with the positively polarized groups of 
membranes.  If the chain of the molecule is long enough it can bind to two or 
more membranes and act as a bridge between protoplasts.  Thus allowing 
adhesion.  PEG also can bind Ca++ and other cations.  These cations, 
especially Ca++, can form bridges between negatively polarized groups on a 
membrane  and PEG thus enhancing adhesion.  To enduce fusion the PEG is 
diluted from the membranes with a washing solution.  As the elution proceeds 
it is thought that a disturbance and redistribution of the electric charges 
occurs over the membrane surface.  Since the two membranes are in intimate 
contact the redistribution affects both of them and causes the observed 
membrane fusion.

reference: Kao and Michayluk, "Fusion of Protoplasts - Techniques" in 
Biotechnology in Agriculture and Forestry, Vol. 8 of Plant Protoplasts and 
Genetic Engineering 1 (ed. by Y.P.S. Bajaj) Springer Verlag, 1989. pp277-288


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