Biological thought and chemical thought : a plea for unification the Linacre lecture for 1938 delivered at Cambridge on May 6th / by Sir Frederick Gowland Hopkins.

  • Frederick Hopkins
Date:
[1938?]
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Licence: Public Domain Mark

Credit: Biological thought and chemical thought : a plea for unification the Linacre lecture for 1938 delivered at Cambridge on May 6th / by Sir Frederick Gowland Hopkins. Source: Wellcome Collection.

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    is fatal, obtain their energy for growth were long obscure. The Cambridge workers have thrown most interesting light on this problem. They have shown on quantitative lines that if substances are present in the medium in suitable pairs, one capable of acting as a hydrogen donator and the other as an acceptor, the processes of hydrogen transport under the influence of dehydrogenases can itself yield sufficient energy for growth. I will mention just one other phenomenon of quite peculiar interest which my colleagues have illuminated, though they were not the ~* first to observe its occurrence. While certain enzymes form part of the permanent constitution of each bacterial species, it would seem that others can be newly acquired as the result of contact with particular molecules in the external medium. ‘These have been called adaptive enzymes in contrast with those which are constitutional. To take an instance which in particular has been studied in my department: it has been long known that certain bacterial cultures can break down formic acid into carbon dioxide and free hydrogen. If Bacillus coli (say) be first grown in a broth . medium completely free from formic acid, it is found, when transferred to a simple medium con. taining the acid, to lack all power to decompose it, whereas a culture identical in origin but grown in the presence of the acid, is afterwards found, even when not growing, to decompose it vigorously. - This is a striking phenomenon which should be borne in mind when we try to form a picture of how enzymes take origin during the growth and development of living cells in general. There is at least some evidence that adaptive enzymes may appear de novo in the tissue cells of animals aS a consequence of some change in the constitution of their internal environment. I do not think it over-bold to believe that here, in elementary form, we have a factor contributing to that fundamental quality of living beings, the power of adaptation. It is sure that chemical adaptations, great or small, accompany all adaptations in form and function. Comparative biochemistry and all that is special in the chemistry of individual organs make this sure. The complexity of the catalytic equipment at such apparently low levels of organisation as that of the bacteria is certainly a striking thing. Dr. Stephenson has pointed out, I think rightly, that we should
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