Biochemistry

BIOCHEMISTRY. - Biochemistry is that part of physiology which studies the chemical composition and the chemical-physical properties of animal or plant organisms in order, subsequently, to interpret the dynamism of the chemical and physico-chemical processes that occur in them. The ultimate and essential aim of biochemistry is to establish the relations that exist between these processes and the manifold manifestations (functions) of life. According to whether the object is a healthy or a diseased organism, we have normal or pathological biochemistry.

The first dawnings of biochemistry go back to Paracelsus (1493-1541) and to the iatrochemists of the 17th century; but only in the last sixty years, after the impulse given to it by Justus V. Liebig (1850), has it developed at a vertiginously accelerated rate and acquired the form and substance of a science in its own right. The advances of biochemistry, besides being connected with those made in this last century by chemistry and physics, are also to be ascribed to the ingenious creation of a multiform and original methodology, suited to the needs of the new science that was arising and that increasingly attracted scholars by its promising fruitfulness. It is beyond dispute that today biochemistry represents the prodigious ferment which, permeating all the biological sciences and medicine in particular, has in a short time succeeded in channeling them toward a new direction, added to the old morphological one, which, though boasting a glorious past, now appears largely exhausted. Among the most recent conquests of biochemistry we shall recall the vitamins, the hormones, the identification of ever new enzymes and of their chemical constitution, the phenomena of intracellular oxidation-reduction, the interpretation of immunological phenomena, the discovery of gamones, of organizers, etc.

In order to arrive at an objective evaluation of the position of biochemistry in the field of the biological sciences, one should bear in mind that the only form of energy available to animals is chemical energy, which they introduce from the external world by means of food. On the other hand, every manifestation of life can be considered, in a broad sense, as an externalization of energy; and since the law of the conservation of energy admits of no exceptions, it follows that the manifestations of life too must be interpreted as the result of transformations of the original chemical energy into other forms of energy (mechanical, osmotic, surface, etc.). Thus, for example, the function of the muscles consists essentially in the transformation of the chemical energy of the fundamental metabolite of the muscles, glycogen, into mechanical energy.

Plant organisms, unlike animal ones, besides chemical energy deriving from the energy-bearing substances that they can take in, also have at their disposal radiant solar energy; but the latter, as soon as it is captured by the plant, is transformed, by virtue of chlorophyllian action, into chemical energy, through the synthesis of organic substances rich in that form of energy. It follows that for plants too, as for animals, the initial energy, from whose utilization the various functions derive, is always chemical energy.

This simple observation would suffice to place biochemistry at the basis of any branch of biology (v.). It indeed aims directly at the physico-chemical determinism of biological functions and tends to detect and to order the links constituting the complex chains of phenomena that exist between a given function and the chemical energy that is the first and necessary reason of that function, through the metabolic processes. Since biochemistry has succeeded in deciphering and knowing the biochemical processes that underlie many phenomena of life, and since its uninterrupted conquests give reason to believe, with well-founded hope, that such knowledge will extend to all phenomena of this kind, the conviction may gain ground that through the continuous progress of biochemistry the ancient and persistent tendency of man to explain life by a simple and exclusive physico-chemical mechanism will, sooner or later, be satisfied. This conviction, however, is the fruit of a superficial impression arising at first glance; for anyone, on the other hand, who penetrates somewhat into the study of biochemistry, the observation soon imposes itself that the ever more sensational advances of this science lead inevitably to the demonstration that above the physico-chemical phenomena occurring in living beings there exists a fact that dominates and transcends them; and this fact is precisely the astonishing coordination with which such phenomena are conducted toward a finality, which only a blind prejudice can attempt to disregard and to deny. Whatever vital externalization we undertake to investigate as to its physico-chemical determinism, we shall always have to reach the conclusion that the physico-chemical processes, which represent the material and energetic substrate of that vital externalization, in their enormous complexity and in their infinite modality of evolving, are in every case coordinated in time and in space in so perfect and so adequate a manner that their result is evidently directed to the satisfaction of some purpose, which is identified with some function of the organism. But in the very act in which a function springs from this complexity of chemical and physical processes, which surpasses every imagination and which is always coordinated, the passage between the material and the immaterial has already occurred, because in the function, precisely because it is such, we are compelled, willingly or unwillingly, always to recognize some finality of a more or less elevated order; and between this finality and the individual chemical and physical processes that have preceded the function to which the finality itself refers, we cannot find any nexus of causality, but only of simple determinism, inasmuch as those processes remain inexorably blind and fatal, as is characteristic of any physico-chemical process.

What therefore distinguishes life, and what biochemistry brings out all the more the more it progresses, is not the infinite possibility of physico-chemical phenomena inherent in tissues and organisms, a possibility surpassing every human inventiveness and every technical ingenuity, realized or realizable, but the precise order with which such phenomena are effected, a condition in turn prerequisite for those even more marvelous events, surrounded by a transcendental character, represented by the functions of the individual organs with their irrepressible finalities, to be delineated upon the albeit wonderful unfolding of those phenomena and finally to burst forth.

It goes without saying that what we have said holds, besides for any function, in a particular way for the introspective functions, in their entire range, from simple sensation to the divining intuition of genius. We may admit, and not concede, that one day, for example, we might succeed in constructing a muscle fiber and in lifting the veil on all the chemical and physical events that condition a contraction; but from these events, which make possible those material muscular contractions that determine the hero's impulse and project him into the ultimate holocaust, we could never rise to the sublimity of his ideal.

In defining b. and its tasks, we took care to give warning that the hope of explaining life by a simple chemical and physical mechanism goes beyond the possibilities of b. itself, notwithstanding its dazzling victories, because at the apex of such mechanism, undeniable in living beings, we always encounter phenomena of a transcendent character, which are precisely those that characterize life itself. But if b. is not the omnipotent goddess that removes or will be able to remove the veil of the mystery of life, it nonetheless remains that this new and fervent branch of b. offers the scholar a field of investigation that shows no sign of having limits and into which one may venture with the boldness and enthusiasm of a pioneer preparing to explore a flourishing region still unknown. It is not to be believed, however, that the virginity of such terrain makes the progress of b. easy and effortless; on the contrary, the difficulties it encounters are certainly greater than those that oppose the progress of chemistry and physics, with which b. shares its methodology.

These difficulties are first of all inherent in the very complexity of biological systems, even if we wish to schematize them after the manner of simple physico-chemical systems. Such systems indeed, whether they are represented by organisms in toto or by their parts, are all colloidal systems and, as such, the course of the biochemical processes that take place in them is influenced by the immensity of interfacially present surfaces, which constitute an independent variable that usually does not figure in the processes studied by pure chemistry and physics and that complicates them beyond measure. Biocolloids (v. COLLOIDI) on the other hand are colloids sui generis, constituted by complex, enormous and extremely labile molecules (proteins); moreover they belong to the class of ampholytes and are endowed with a very high power of imbibition, which can vary from moment to moment, according to infinite circumstances internal and external to the organisms themselves. Not only that, but the site where biochemical processes take place is represented by the cells, of which every living being is formed, which, as is well known, are microscopic units. It is in this infinitesimal environment that the biochemist must grasp and investigate chemical processes, which are often of a bewildering complexity in number, variety and interference, and it is in this environment, where the integrity of the most delicate structures of the protoplasm exerts a fundamental influence on the course of the biochemical processes carried out in it, that the biochemist must venture, renouncing all those reagents which, by their energetic action, usefully employed by the pure chemist, would be disastrous, with regard to the tasks the biochemist sets himself, if he were to apply them in his own research.

As can be seen, b., having before it a boundless and unexplored field, must proceed amid technical difficulties that are often discouraging, which further accentuates the value of its uninterrupted conquests.

Achille Roncato