Fig. 5-2. Molecular weight determinations by SDS 

 PAGE and by silver stain of the two S-proteins. A) The 

 SDS gel shows 2 bands for SP-I (584 ng) at molecular 

 weights of about 60,000 and 40,000 in lane 3. Lane 5 has 

 a single detectable band at a molecular weight of about 

 62,000 for the SP-II (155 ng) . Lanes 1 and 7 are 

 molecular weight markers with MW as indicated. B) The 

 silver staining technique was also used to determine 

 molecular weights of the S-proteins. Lanes 1, 9, and 16 

 show molecular weight markers. Lanes 2 through 7 

 represent SP-I and lanes 11 through 14 represent SP-II at 

 various stages of purification as follows: 



Lane Protein purification step Molecular weight (s) 



2 



SI 



25ul 



Affinity pure 





60, 



,000 



40, 



,000 







3 



SI 



lOul 



Affinity pure 





60, 



,000 



40, 



,000 







4 



SI 



25ul 



DEAE- cellulose 





60, 



,000 



40, 



,000 



29, 



,000 



5 



SI 



lOul 



DEAE- cellulose 





60, 



,000 



40, 



,000 



29, 



,000 



6 



SI 



lOul 



Affinity pure 



(AB) 



60, 



,000 



40, 



,000 



29, 



,000 



7 



SI 



25ul 



Affinity pure 



(AB) 



60, 



,000 



40, 



,000 



29, 



,000 



11 



S2 



25ul 



Affinity pure 



(1) 



62, 



,000 











12 



S2 



lOul 



Affinity pure 



(1) 



62, 



000 











13 



S2 



25ul 



Affinity pure 



(2) 



62, 



,000 











14 



S2 



lOul 



Affinity pure 



(2) 



62, 



000 











(AB) is purified enzyme from several runs that were 

 combined, passed through the affinity column a third time 

 and concentrated. For SP-II the (1) represents the 

 purified protein after the first pass through the 

 affinity column and (2) represents combined column runs 

 of SP-II passed a second time through the affinity column 

 and concentrated. 



