A method for two-dimensional electrophoresis of proteins from green plant tissues.

A method of extraction of proteins from green plant tissues for two-dimensional electrophoresis is presented. The method is demonstrated on barley and potato leaves and on spruce needles for use in isoelectric focusing as well as in nonequilibrium pH gradient electrophoresis. The following three-step procedure was used: (i) The tissue was ground in liquid nitrogen and then in a pH 5.0 buffer with thiourea added to inhibit phenoloxidase and polyvinylpyrrolidone to bind phenolic compounds. (ii) The proteins were precipitated with acetone at -20 degrees C. (iii) The proteins were dialyzed. Protease activity was generally not a problem during this procedure.