BIOCHIMICA. - 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 within them. The ultimate and essential purpose of biochemistry is to establish the relations existing between these processes and the manifold manifestations (functions) of life. Depending on whether the object is a healthy or diseased organism, we have normal or pathological biochemistry.
The earliest beginnings of biochemistry go back to Paracelso (1493–1541) and to the iatrochemists of the 17th century; but only during these last sixty years, after the impetus given to it by Giusto V. Liebig (1850), has it developed with vertiginously accelerated speed and acquired the form and substance of a science in its own right. The progress of biochemistry, besides being connected with the advances made during this last century by chemistry and physics, must also be attributed to the ingenious creation of a varied and original methodology, suited to the needs of the new science that was emerging and that increasingly attracted scholars by its promising fruitfulness. There can be no doubt that today biochemistry represents the prodigious ferment which, permeating all the biological sciences and medicine in particular, has succeeded in a short time in directing them toward a new orientation, added to the old morphological one which, though it can boast a glorious past, now appears to have been largely exhausted. Among the most recent achievements of biochemistry may be mentioned vitamins, hormones, the identification of ever new enzymes and of their chemical constitution, intracellular oxidation-reduction phenomena, the interpretation of immunological phenomena, the discovery of gamones, organizers, etc.
In order to arrive at an objective assessment of the position of biochemistry in the field of the biological sciences, it should be borne in mind that the only form of energy available to animals is chemical energy, which they take in from the external world through food. On the other hand, every manifestation of life may be considered, in the broad sense, as an expression of energy; and since the law of conservation of energy admits of no exception, it follows that 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 muscles essentially consists in the transformation into mechanical energy of the chemical energy of the fundamental metabolite of the muscles, glycogen.
Plant organisms, unlike animal organisms, possess not only chemical energy, derived from the energy-yielding substances that they can absorb, but also solar radiant energy; yet the latter, as soon as it is captured by the plant, is transformed, by virtue of chlorophyll action, into chemical energy through the synthesis of organic substances rich in this 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 alone would suffice to place biochemistry at the biology (v.). It is in fact directed immediately toward the physico-chemical determinism of biological functions and seeks to ascertain and arrange the links constituting the complex chains of phenomena that intervene, through metabolic processes, between a given function and the chemical energy which is the primary and necessary reason for that function. Since biochemistry has succeeded in deciphering and understanding the biochemical processes underlying many phenomena of life, and since its uninterrupted achievements give well-founded hope that this knowledge will extend to all phenomena of this kind, one may be led to the conviction that, through the continual progress of biochemistry, the ancient and persistent human tendency 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 first impression; for anyone who penetrates somewhat into the study of biochemistry soon finds himself compelled to recognize that the increasingly sensational advances of this science inevitably lead to the demonstration that above the physico-chemical phenomena occurring in living beings there exists a fact which dominates and transcends them; and this fact is precisely the astonishing coordination by which such phenomena are directed toward an end which only blind prejudice can attempt to disregard and deny. Whatever vital manifestation we undertake to investigate in its physico-chemical determinism, we must always reach the conclusion that the physico-chemical processes which represent the material and energetic substratum of that vital manifestation, in their enormous complexity and in their infinite modes of development, are in every case coordinated in time and space so perfectly and so appropriately that their result is evidently directed toward the fulfillment of some purpose, which is identified with some function of the organism. But at the very moment when a function arises from this complexity of chemical and physical processes, surpassing all imagination and always coordinated, the transition from the material to the immaterial has already taken place, because in a function, precisely insofar as it is such, we are compelled, willingly or unwillingly, always to recognize some purpose of a more or less elevated order; and between this purpose and the individual chemical and physical processes that have preceded the function to which the purpose itself refers, we are unable to find any causal nexus, but only one of simple determinism, insofar as these processes remain inexorably blind and fatal, as is characteristic of every physico-chemical process.
What therefore distinguishes life, and what biochemistry causes to stand out all the more as it advances, 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 in which such phenomena take place, a condition that is in turn prerequisite for those still more marvelous events, surrounded by a transcendental character, represented by the functions of the individual organs with their irrepressible purposes, to take shape and finally emerge upon the admittedly marvelous course of these phenomena.
It goes without saying that what we have said applies not only to every function, but in a particular manner to introspective functions throughout their entire range, from simple sensation to the divining intuition of genius. We may admit, without conceding, that one day, for example, it may prove possible to construct a muscle fiber and to lift the veil from 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 impetus and hurl him into the ultimate holocaust, we could never rise to the sublimity of his ideal.
In defining b. and its tasks, we have taken care to warn that the hope of explaining life through a simple chemical and physical mechanism goes beyond the possibilities of b. itself, despite its dazzling victories, because at the apex of such mechanism, undeniable in living beings, we always encounter phenomena of a transcendent nature, which are precisely those that characterize life itself. But if b. is not the all-powerful goddess who removes or will be able to remove the veil from the mystery of life, it nevertheless remains true that this young and fervent branch of b. offers the scholar a field of investigation that shows no sign of having limits, and in which one may venture with the boldness and enthusiasm of a pioneer setting out to explore a flourishing region still unknown. It should not, however, be thought 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 opposing the progress of chemistry and physics, with which b. shares its methodology.
These difficulties are first and foremost inherent in the very complexity of biological systems, even if we wish to schematize them as simple physico-chemical systems. Such systems, in fact, whether represented by organisms in toto or by their parts, are all colloidal systems and, as such, the course of the biochemical processes taking place within them is influenced by the immense number of interfacial surfaces present, constituting an independent variable that ordinarily does not appear in the processes studied by chemistry and pure physics and that complicates them immeasurably. Biocolloids (v. COLLOIDI), moreover, are colloids sui generis, made up of complex, enormous, and extremely labile molecules (proteins); they belong to the class of ampholytes and possess a very high imbibition capacity, which may vary from moment to moment, depending on infinite circumstances internal and external to the organisms themselves. Not only this, but the site where biochemical processes occur is represented by the cells of which every living being is composed, and which, as is well known, are microscopic units. It is in this infinitesimal environment that the biochemist must grasp and investigate chemical processes that are often astonishingly complex in number, variety, and interference; and it is in this environment, where the integrity of the extremely delicate structures of the protoplasm exerts a fundamental influence on the course of the biochemical processes taking place within it, that the biochemist must venture, renouncing all those reagents whose vigorous action, though usefully employed by the pure chemist, would be disastrous, with regard to the aims pursued by the biochemist, were he to apply them in his own research.
As can be seen, b., having before it an immense and unexplored field, must proceed amid often discouraging technical difficulties, which makes the value of its uninterrupted achievements all the greater.