Acta Physiologica 19. (1961)
1-4. szám - Szent-Györgyi A.: On Energy Transformation
294 A. SZENT-GYÖRGYI that after five years of struggle I can see which way the solution lies even if I do not have it yet. The situation seems to me to be simple and logical. Biochemistry went into bloom at the end of the last century. At this time the atom was an indivisible unit and molecules were structures built of such atoms. Our bodies being built out of molecules, it seemed that all we had to do to understand life was to take the body apart into molecrdes and analyze these molecules by means of methods of classical chemistry and physico-chemistry. Biochemistry owes most of its great successes to this molecular outlook, and so the best preparation for a research career seemed to be a thorough acquaintance with classical chemistry, and so most biochemists got their education in this field. During the last decades, however, physics, penetrating into the interior of the atom, created a new science, quantum mechanics, which gives a new foundation to chemical thinking. About highly organized systems it introduced new concepts, like that of the “solid state”, based on the electronic structure of matter, — and, we should remember, all complex functions are linked to the more or less solid structure. Biochemistry did not follow into this new domain. This new domain of the submolecular seemed to hold the key to the understanding of the phenomena, which I mentioned, in the analysis of which biochemistry was unsuccessful. In the reactions, in the analysis of which biochemistry was successful, which can be reproduced in homogeneous solutions, the strict molecular concept is a good guide. However, in the second group of reactions, which we do not understand, which are linked to complex structure and to the solid state, the molecular concept breaks down, though, these complex structures can be dismantled into single molecules. The situation is analogous to that in the structure of a house which can be broken down into bricks. However, the study of bricks will never explain what a house is. In a house the bricks join to walls, to higher structures which give sense to them, and in studying the house, the idea of bricks disappears. So in the study of the living structures, the molecular concept is fizzling out. Already, at Szeged, I began looking for possibilities of establishing a new way of outlook. Just then the idea of “solid state” began to be established and I hoped that this would give us the foundation needed for a new biochemistry. By “solid state” the physicist mostly means systems built of identical units, units which are arranged with great regularity very close to one another, as is the case within a crystal. In such a system the potential walls, separating the single molecules, may be very low and the whole crystal may act as one single unit. The most common example of the fusion of molecules or atoms, is the copper wire which conducts electricity, in which an electron put in at one end may be tapped off at the other, miles apart. This copper wire is also built of atoms but the dividing potential walls between these break down and common energy bands are established. However, later I began to doubt whether this concept