10 Essays in Biochemistry 



to be analyzed, that caution is necessary in deducing the formula of a 

 poly acetylene from that of its reduction products. 



Data useful for spectrophotometric correlations have been obtained 

 in some instances. For example, the absorption maxima of diatretyne 

 amide, in which the endiyne system is conjugated at either end (to a 

 carboxyl carbonyl at one end and an amide carbonyl at the other end), 

 are essentially the same as would be expected for an endiyne system 

 conjugated only to a carboxyl group, and the spectrum of diatretyne 

 nitrile resembles closely that of an entriyne system. Thus, the nitrile 

 grouping as it occurs in this compound acts chromophorically like 

 another acetylenic bond, whereas the conjugated carboxyl grouping 

 again has no pronounced effect on the spectrum. 



The existence of polyacetylenic compounds of biological origin * 

 poses many questions of general biological interest, and their isolation 

 and structural elucidation pave the way for attacking some of the 

 problems raised. 



From a metabolic standpoint, the existence of polyacetylenes of 

 biological origin presents several problems. The first question which 

 arises, naturally, is one concerning the origin of these compounds. 

 By what series of reactions do these highly unsaturated compounds, 

 of chain lengths as short as C s and as long as Ci 8 , arise? What are 

 their immediate precursors? Are they formed by combinations of 

 shorter-chain unsaturated compounds or by dehydrogenation of com- 

 pounds of similar chain length? Growth of poly acetylene-producing 

 organisms using an isotopic carbon source may help to provide some 

 of the answers. The fate of these compounds in the organism is also 

 an unexplored problem. It seems reasonable to suppose that highly 

 reactive compounds like the polyacetylenes may be not merely end 

 products of metabolism but, rather, intermediates. By using labeled 

 polyacetylenes produced either by the fungus or synthetically, it should 

 be possible also to attack this problem. 



The general question of relation of structure to antibiotic activity 

 arises also in connection with polyacetylenes. Neither the synthetic 

 polyacetylenes nor those isolated from higher plants have been tested 

 systematically for antibiotic activity. However, there are several facts 



* The term "naturally occurring" as applied to polyacetylenes isolated from 

 fungal culture liquids was used in contradistinction to "synthetic" but is, perhaps, 

 somewhat ambiguous in its implications. Nothing is known about the production 

 of these compounds by fungi in nature since they have been isolated only under 

 laboratory conditions. A term such as "biologically produced," suggested by 

 Dr. Selman Waksman, or "of biological origin" might, therefore, be preferable. 



