BIOGRAPHICAL MEMORANDA 



light, and thus contributed to their eventual solution. Furthermore, 

 the comparative biochemical approach often indicated an immediate 

 answer to some less baffling problems. A good example is furnished 

 by the identification of a pigment produced by Pseudomonas aureqfa- 

 ciens, discovered in Kluyver's laboratory, as phenazine-a-carboxylic 

 acid. It is significant that Kluyver [1956], in his posthumous publi- 

 cation on the subject, introduced the experimental part in the follow- 

 ing words: 



'It is well known that the genus Pseudomonas comprises several pig- 

 ment-producing species, and that in all cases in which the constitution 

 of these pigments has been established they have been found to be 

 phenazine derivatives. . . . (Thus it seemed) worthwhile to look out 

 for further pigment-producing species within the genus Pseudomonas 

 in order to check if still other phenazine derivatives occur as natural 

 products. The opportunity presented itself in 1936 when Mr. Bouman, 

 working in this laboratory, incidentally came across a bacterium which 

 was easily identified as a Pseudomonas species, and which attracted atten- 

 tion by an ample formation of yellow crystals in its colonies' (p. 406). 



But the element of naivete was not lacking either; it cannot be 

 denied that Kluyver sometimes found it hard to resist the temptation 

 to promulgate an explanation of certain phenomena even in the ab- 

 sence of an adequate body of factual information to support it ; and 

 the tendency to be satisfied with such an explanation if only it sup- 

 ported the concept of comparative biochemistry and the 'unitary 

 theory' may occasionally have delayed more searching studies. 



This aspect is illustrated by the studies on yeast metabolism that 

 were intended to show that certain observations made elsewhere, al- 

 though at first sight contradicting Kluyver's theory, could nevertheless 

 be reconciled with it. The investigation of the co-zymase problem 

 discussed earlier was a case in point; here another example may be 

 mentioned. 



After having invoked an identical series of primary reactions for 

 the transformation of sugar into two triose moieties for the explanation 

 of all known sugar fermentations, it was, to use a favourite phrase of 

 his, 'tempting to postulate' that the same conversions would also be in- 

 volved in the initiation of the oxidative degradation of sugars by many 

 different organisms. This 'unitary theory' was threatened when Lunds- 

 gaard published his studies on the effect of mono iodoacetic acid on 



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