BIOCIII'MIS'FRY OI' I'LANIS 



portant effect on certain of the pliosphorylation processes in muscle, 

 withi an antagonistic action by calcium. Studies of this ty])e, applied 

 to the enzyme systems of higher plants, would obviously be of great 

 significance for plant nutrition. 



If we turn to the essential element phosphorus, great encourage- 

 ment is gained for the view that biochemical research on animal 

 tissues and on microorganisms can serve as a guide for extension of 

 research on the metabolism of the plant. In fact, current research on 

 phosphorus metabolism of various organisms has far-reaching implica- 

 tions for problems of plant nutrition from both a theoretical and 

 practical standpoint. 



Following the work of Cori on the phosphorolytic system in 

 animal tissues which brings about the synthesis of glycogen from 

 glucose-1 -phosphate came the discovery by Hanes (5) "that an enzyme 

 system can be prepared from plant tissues (potato, peas) which cata- 

 lyzes reversible phosphorolytic reactions by which starch can he syn- 

 thesized in vitro. Physical and chemical studies have been made of 

 the synthesized starch, and its structure compjared with that of ii;itural 

 plant starch (7,11). 



The conclusion is that the aitificially synthesized starch repre- 

 sents only the amylose component of natural starch, that is, the one 

 made up of long chains of glucose units, whereas the natural starch 

 also includes a component characterized by a branched-chain structure. 

 Recently, the failure to reproduce artificially the complete natural 

 starch was apparently overcome. A preliminary report has been 

 made of the isolation of another enzyme system from potato which can 

 accomplish the synthesis in vitro of the amylopectin component of 

 starch, with the branched-chain structure (8). The investigations 

 as a whole on this question therefore represent clarification of the role 

 of an essential inorganic element in synthesis by the plant of one of its 

 most important carbohydrates. It is not difficult to appreciate the way 

 in which this addition to plant biochemistry may aid in the guidance 

 of researches in plant nutrition with reference to the utilization of 

 phosphate. From the agricultural point of view, the information now 

 available may well become of value in appraising the adequacy of the 

 phosphate supply for high yields or starch content of a crop, especially 

 as further research provides more data on concentiations of various 

 forms of phosphate in the plant under diverse nutrient and atmospheric 



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