BIOGRAPHICAL MEMORANDA 



The first was his general philosophical outlook which made him 

 wary of the tendency to explain biochemical reactions in terms of 

 events mediated by specific enzymes. As long as there was no prospect 

 that the chemical nature of the postulated enzymes could be eluci- 

 dated or even approximated, this practice seemed like futile para- 

 phrasing without adding anything to our understanding of the pro- 

 cesses themselves. Worse, this approach, which had already induced 

 many biochemists to name a specific enzyme for every biochemical 

 reaction that could be surmised to exist, might easily lead to a false 

 sense of comprehension, and to a mental image of a living cell as the 

 depository of a vast number of such catalysts, distributed without 

 rhyme or reason; a bag of enzymes rather than a smoothly func- 

 tioning unit. Alternatively, the development of general principles 

 that could help to account for the multifarious activities of living 

 organisms in a chemically intelligible manner had given rise to the 

 concepts of hydrogen transfer and the unity in biochemistry, and 

 eventually to the notion that a single property should suffice to ex- 

 plain the many conversions a cell is capable of performing. This ap- 

 proach was clearly antagonistic to the one based upon the assumption 

 of a haphazard multiplicity. It had, moreover, been fruitful; it was 

 dedicated to a search for still greater unification; and it could be 

 further exploited. If finally we remember the difficulties inherent in 

 procuring extracts of nonhydrolytic enzymes, we can readily ap- 

 preciate Kluyver's belief that enzyme research would not be parti- 

 cularly rewarding. 



Secondly, this attitude appeared to be vindicated by the results of 

 the investigation on the coenzyme of alcoholic fermentation that he 

 carried out with the collaboration of Struyk [1928]. As already stated, 

 the exceedingly complex nature of an extract such as zymase made it 

 seem hopeless to attempt a chemical characterization of the specific 

 catalyst. But Harden had discovered that a yeast juice could be de- 

 prived of its fermenting capacity by dialysis or ultrafiltration, and that 

 the residue could be restored to activity by the addition of the dial- 

 ysate or filtrate. Thus the factor in the dialysate responsible for this 

 behaviour was evidently a substance of relatively small molecular size; 

 in addition, it had been found resistant to prolonged boiling. These 

 properties of the so called co-zymase indicated that it would be more 

 amenable than zymase itself to chemical investigation, and some bio- 



