Purification of Primary Factor

Thus far, SubbaRow and associates had isolated various accessory factors which, in themselves, were shown to be of no therapeutic value. Their subsequent work on the purification of the primary factor will now be described (107) (Table XIV). Fractions H and I prepared as described in the table were tested for their activity. 

They also prepared fraction I without the use of absorption by Fuller s earth (Table XV). 

Fraction I, a white microcrystalline material, was found to be readily soluble in water. Its sulfate, readily soluble in dilute alcohol, but quite insoluble in absolute alcohol, was prepared by acidifying an aqueous solution of fraction I to pH 2.5 with H2SO4 and adding acetone and ether. 

Analysis (of the sulfate, which decomposes without melting above 290 ). 

Its amino nitrogen was determined after interaction with nitrous acid at the end of five minutes and at the end of 60 minutes  

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