Protein Chemistry - Part 1 - General Protein Chemistry - Ashmarin I. P. 1968

Introduction
Proteins and Living Matter

Proteins occupy a unique position among the compounds that make up living matter. As early as 1874, summarizing the empirical knowledge accumulated in natural science by that time, F. Engels wrote: "Life is the mode of existence of protein bodies, and this mode of existence essentially consists in the constant self-renewal of the chemical constituents of these bodies. Wherever we find life, we find it associated with some protein body, and wherever we find a protein body that is not undergoing decomposition, we invariably encounter the phenomena of life." Engels' definition remains significant to this day as a remarkable example of a dialectical-materialist generalization of scientific achievements. It must be admitted that no DEFINITION OF LIFE of comparable depth and precision, matching the current level of scientific development, has yet been proposed. The question of such a definition is currently the subject of widespread Structure/133.html">Discussion. Without going into the various directions of this discussion here, let us highlight A number of propositions that have become quite clear to date.

Proteins in the modern sense of the term, taken by themselves, are not the sole defining and most characteristic component of living matter. Nucleic Acids, at the very least, must also be included among such compounds. Furthermore, all known forms of living matter are complex supramolecular structures rather than isolated molecules of proteins, nucleic acids, or Nucleoproteins. It is worth noting, incidentally, that the term "protein bodies" used by Engels corresponded in the science of his time not to individual proteins, but to products known to contain many non-protein components and essentially close to cellular protoplasm.

As for the "mode of existence" of living matter, alongside the universal recognition of The process of self-renewal of all its chemical constituents, important features of metabolic processes in living organisms have been established. The most essential of these is the energetic orientation of these processes. Life can be maintained only through the constant consumption of energy released by the transformation of environmental substances. This energy is necessary to maintain a high degree of Organization in biological structures. The latter process is in dialectical contradiction with the more general process of increasing system Entropy. One might say that life is a struggle against entropy.

Consequently, Engels' definition cited above can be expressed in the light of modern scientific achievements as follows.

Life (in the forms known to us) is the mode of existence of supramolecular systems whose characteristic components are proteins and nucleic acids; this mode of existence consists in the self-renewal of all chemical constituents of the systems, ensuring the maintenance and development of anti-entropic states at the expense of increasing the entropy of environmental substances.

Here, self-renewal is understood to mean not only the self-renewal of individual system components, but also the self-Replication of the systems as a whole. This definition once again emphasizes the special role of proteins in living matter.