TOO MACROMOLECULAR COMPLEXES 



lipoproteins. No complexing could be achieved with the albumins, 

 gelatin, or peptones. In most cases there was difficulty in resolubil- 

 izing the precipitate, and pheophvtin was formed. The complex was 

 not soluble in reagents which are known to solubilize lipoproteins, 

 but was readily soluble in digitonin. Attempts to demonstrate that 

 these complexes are photoactive were on the whole unsuccessful. 

 The difficulty with this procedure may be that the acetone causes 

 denaturation of the proteins. An analysis of two such complexes, 

 the chlorophyll-horse serum and the chlorophyll-y globulin, is shown 

 in Table 2. 



TABLE 2 

 Pigment-Protein Complex 



M 



p ( Mol wt calcu- 



( Moles chloro- n lated from 



Complex phyll/1 ) ( Mg Nitrogen/ml ) p and n ) 



Chlorophyll 



with horse sermn 11.4 X 10-' 1.2 69,300 



Chlorophyll 



with 7-globulin (bovine) .. 2.42x10"'' 0.62 173,000 



Chloroplastin. Another possibihty was to extract the whole 

 chloroplastic material from the chloroplasts by surface-active agents. 

 Detergents in solution form colloidal aggregates, micelles, consisting 

 of many molecules of detergent clumped together. Such micellar 

 bodies have a very strong attraction for many of the more complex 

 dye molecules. Commercially available non-ionic and ionic surface 

 agents were used to extract the pigment complex from the chloro- 

 plasts. The non-ionic recrystallized detergents, Nacconal NRSF ^ 

 and digitonin,^ were found superior to all other surface-active agents 

 tested. These are nitrogen-free detergents and therefore do not 

 interfere with the protein analyses. Although the ionic detergents 

 Alkonal B, glycocholate, and taurocholate were noted as good 

 solubilizing agents, they did not preserve the spectral and other 

 properties of the chlorophyll- complex. The digitonin-extracted pig- 

 ment-complex therefore serves as the best experimental material. 



■' Nacconal NRSF, anionic organic detergent, alkyl aryl sulfonate, Allied Chemical 

 and Dye Corporation. 



•* Digitonin, anionic detergent ( C5.-,H[,o02o ) D-58, Fisher Scientific Co. 



