Hormone in Plant Tissue 



321 



157 (2117) 



The demonstration of a hormone in plant tissues to be known 

 as "glucokinin." 



By J. B. COLLIP. 



[From the Department of Biochemistry of the University of 

 Alberta, Alberta, Canada.] 



The demonstration by the writer, in collaboration with Mac- 

 Leod, Banting, and Best, that active preparations of the internal 

 secretion of the pancreas conferred upon the depancreatized dog 

 the power of glycogen formation led at once to the idea that 

 wherever glycogen occurred in nature, a hormone similar to that 

 produced by the islet cells of the pancreas would probably be 

 found. Three obvious places to look for such a substance were 1 

 tissues of lower animals rich in glycogen such as the clam, 2 yeast, 3 

 fungi. The writer 2 was immediately successful in demonstrating 

 the presence of such a hormone in clam tissue. Yeast was also 

 investigated continuously for many months, and on January 26, 

 1923, after more than a score of failures, an extract of yeast was 

 obtained which produced marked hypoglycemia in a normal rab- 

 bit (blood sugar 0.046 per cent). Since that date extracts of 

 yeasts which have similar properties have been prepared by five 

 different methods. The administration of such a potent yeast 

 extract to a depancreatized dog also caused a marked fall in the 

 percentage amount of blood sugar and a great decrease in the 

 hourly excretion of sugar. As the yeast organism is a plant of 

 the least differentiated type in the vegetable kingdom, the idea 

 occurred to the writer that, as all plants are sugar burners as well 

 as producers, the preparation of the sugar molecule for combus- 

 tion in the protoplasmic fire of the plant cell might be quite a 

 secondary affair and be dependent, as Winter and Smith 3 have 

 suggested, on the preliminary formation of y glucose, the com- 

 bustion of sugar or the polymerization of the same being pri- 

 marily dependent upon presence of the y form of glucose. If this 



1 Banting, F. G., Best, C. H., Collip, J. B., MacLeod, J. R, R., and Noble, 

 E. C, Trans. Boy. Soc. Can. 1922, xvi. 



2 Collip, J. B., J. Biol. Ch'em., 1923, lv. XXXIX. 



3 Winter, L. B., and Smith, W., J. Physiol., 1922, lvii, 100. 



