28 

 amount was removed for dialysis in Epps-KOH buffer and used 

 as a crude extract. Ammonium sulfate was added to give 75% 

 of saturation. From the slurry, 70 ml were removed and 

 prepared for use as a concentrated crude extract . To the 

 remaining slurry, 40 g of Celite 545 was added, stirred, 

 poured into a column (90 ml vol) and the eluate collected 

 into a cylinder. The column was washed with 65% (NH4)2S04 of 

 saturation in Epps-KOH buffer (about 180 ml) and 8-ml 

 volumes were collected. Buffer with (NH4)2S04 at 55% of 

 saturation (120 ml) was added, followed by a shallow 

 gradient of 600 ml from 55% to 45% of (NH4)2S04 saturation in 

 Epps-KOH buffer. A step gradient of 180 ml of buffer at 45% 

 of (1^4)2804 saturation was applied before the second 

 gradient of 45% to of (NH4)2S04 saturation (400 ml) was 

 added. A final wash of 120 ml of Epps-KOH buffer completed 

 the elution schedule. 

 Gel filtration 



A Sephadex G-200 gel filtration column was used to 

 determine the native molecular weight of the S-proteins. 

 The column was equilibrated with 50 mM Epps buffer, pH 8 . 6 

 and DTT. Three ml of concentrated crude extract, and 

 concentrated SP-I or SP-II combined with . 1 Af sucrose were 

 applied individually to the same column (column vol of 471 

 ml, void vol of 119.4 ml) . Protein standards of 5 mg each. 



