BERNARD L. STREHLER 217 



It was clear that the compound was lipoidal in nature and that it 

 could be purified by partition between organic solvents. Finally, a 

 procedure yielding a material of considerable purity was devised. It 

 consisted essentially of the following steps: (1) extraction of ace- 

 tonized powders with chloroform, (2) partition between hexane and 

 5% HoO-95% methanol, (3) precipitation of impurities with acetone, 

 (4) precipitation of impurities from small volumes of hexane, chloro- 

 form, and methanol, and finally (5) suspension in IN NaOH and pre- 

 cipitation with HCl. 



The material at this point was a yellowish-white sludge, sparingly 

 soluble in water, but relatively more soluble in strong base and 

 organic solvents. Its activity was such that a small fraction of a 

 microgram per milliliter produced a five- to tenfold increase in 

 luminescence. 



TABLE I 



Comparison of Apparent Dissociation Constants and Maximum Rates of 

 Luminescence in the Presence of Various Long-Chain Aldehydes 



Aldehyde K^ X 10« M Max. Rate (relative) 



Ct 84.0 28 



Cs 20.8 67 



C9 13.3 59 



Cio 4.1 133 



Cii 2.36 52 



C16 3.56 81 



A variety of qualitative organic tests was applied in order to elimi- 

 nate certain groups of lipids as possibilities. The nitrogen content was 

 very low (ca. 1-2%), as was phosphorus, while a fuchsin aldehyde 

 test was strongly positive. Treatment of the material with 2,4-dinitro- 

 phenylhydrazine gave a good yield of the dinitrophenylhydrazone in 

 crystalline form. Attempts to decompose this derivative and recover 

 activity were unsuccessful. The recrystallized dinitrophenylhydrazone 

 exhibited a sharp melting point at 104-105° C. Since this melting point 

 is in the region ascribed to the derivatives of long-chain fatty alde- 

 hydes, we obtained some aldehydes from the stockroom and, although 

 benzaldehyde, acrylaldehyde, and butyraldehyde were not active, syn- 

 thetic heptaldehyde produced a marked increase in luminescence, one 



