114 



BIOCHEMICAL SYSTEMATICS 



covered tetrapeptide, called malformin (Takahashi and Curtis, 1961), 

 reported from Aspergillus niger, very little work on specific higher 

 peptides is available. 



Haas (1950) reported on the peptides from four species of 

 marine algae. The breakdown of amino acids derived from the hydrol- 

 ysis of these algal peptides follows: 



Since these peptides do not occur in detectable amounts in 

 summer months, Haas proposed that lack of light in winter interferes 

 with normal protein synthesis leading to the formation of mixtures of 

 peptides (intermediates?). 



It is possible that at some future time alteration of normal 

 metabolism by exposure to stress will disclose abnormal but sys- 

 tematically enlightening metabolic pathways; that is, the accumula- 

 tion of substances normally found only in small amounts, such as 

 citrulline in flax described earlier, if enzymatically controlled, would 

 provide clues to relationships. Hoffman (1961) observed that several 

 species of the green alga, Oedogonium, could not be distinguished 

 chromatographically until cultures were allowed to remain in stale 

 media. Under these suboptimal conditions, a number of additional 

 compounds then appeared, some of which were species-specific. 



In the older botanical literature there are a number of studies 

 of seed proteins. Some of the results are suggestive of taxonomic 

 affinities. In general the studies are of rather slight value because the 

 proteins are characterized somewhat crudely. One of the more recent 

 comparisons of seed proteins (of grasses and legumes) is that by 

 Danielsson (1949). His work consisted essentially of studying the 

 globuHn fractions by ultracentrifugation. The information yielded by 

 such techniques relates to the number of major globulin types, their 

 relative molecular weights and their relative abundance. The data 

 may be expressed in the form of a graph (Fig. 6-4), each peak 

 representing a component and the height of the peak its amount. To 



