The Chemical Definition of the Essence of Life

1. Life’s Components Originate from the Environment

Every element within a living organism derives from the natural environment. Cellular proliferation through infinite division represents the transformation of environmental substances into biological components. Thus, intracellular reactions-whether single or multi-step-must exist to convert environmental substances into every constituent of life:

Natural environmental substances → “Component of life” (Reaction formula 1)

This reaction reveals critical biochemical insights: the entire organism acts both as a “product” of environmental transformation and a “catalyst” enabling such transformation. Natural environmental substances cannot spontaneously convert into biological components; instead, pre-existing intracellular components (enzymes and other substances), termed “Conditional Substances” (C1,C2,C3...Cx), mediate this process.

Natural environmental substances → Under the action of “Conditional Substances” (C1,C2,C3...Cx) → “Component of life “ (Reaction formula 2)

Importantly, these catalytic components, termed “Conditional Substances” (C1,C2,C3...Cx), are themselves products of Reaction 2. Substituting these into Reaction 2 yields:

Natural environmental substances → ((C1,C2,C3...Cx)-mediated) → (C1,C2,C3...Cx) + Other products (Reaction formula 3)

Reaction 3 demonstrates that Conditional Substances catalyze their own regeneration, doubling their quantity with each cycle. This “automatically perpetual self-synthesizing cycle” underpins the persistent repetition of biochemical processes in life.

2. Identification of Conditional Substances

Conditional Substances are intracellular agents that drive environmental substances into biological components. Enzymes (proteins) are primary constituents, as no biochemical reaction proceeds without them. Nucleic acids (DNA, RNA) are also critical: DNA replication requires templates, while RNA synthesis depends on DNA and RNA polymerase. Vitamins, lipids, carbohydrates, and small molecules, though essential for metabolism, do not directly catalyze environmental transformations and thus are excluded. Only proteins and nucleic acids qualify as Conditional Substances.

3. Evidence of the “Dual Synthesis Reaction” in Cells

Proteins and nucleic acids form a “Dual Synthesis Reaction” (DSR), wherein their synthesis is catalyzed by their own products. Table 1 summarizes the Conditional Substances required for DSR in cells (including eukaryotes):

- DNA replication: Template DNA, helicases, single-strand binding proteins, topoisomerases, primases, DNA polymerases, ligases.

- RNA synthesis: DNA template, RNA polymerases, promoters, transcription factors, terminators, spliceosomes.

- Protein synthesis: DNA/mRNA templates, tRNA, rRNA, aminoacyl-tRNA synthetases, peptidyl transferases, elongation factors.

All listed Conditional Substances are exclusively proteins or nucleic acids. Raw materials (amino acids, nucleotides) and energy sources (ATP, GTP) are environmental derivatives and excluded from Conditional Substances.

4. The Role of Proteins in DSR

Beyond Table 1, all cellular proteins directly or indirectly serve DSR. Enzymes involved in glycolysis, the citric acid cycle [3], or amino acid/nucleotide synthesis supply energy and raw materials [4]. Membrane-forming proteins (e.g., phospholipid synthases) maintain intracellular stability [5], indirectly supporting DSR. Structural proteins (e.g., cytoskeletal fibers) and motility proteins (e.g., flagellin) [6] enhance nutrient acquisition. Critically, every protein and nucleic acid is both a product and catalyst of DSR, perpetuating the cycle.

5. Chemical Definition of Life’s Essence

At the molecular level, proteins and nucleic acids form an automatically perpetual cycle:

1. DNA encodes all proteins and RNAs required for DSR [7].

2. Protein synthesis executes DNA’s genetic instructions, regenerating enzymes and nucleic acids.

3. Newly synthesized proteins and nucleic acids perpetuate DSR, doubling their population with each cycle.

This cycle sustains all cellular chemistry, driving perpetual synthesis of identical biomolecules-the hallmark of life. Thus, “Life is an automatically perpetual self-synthesizing cycle composed of specific proteins and nucleic acids.”

Implications

Understanding life’s chemical essence is pivotal for resolving origins-of-life questions and enabling synthetic biology. Artificial life synthesis may be achievable by replicating Conditional Substances listed in Table 1, though such experiments carry significant risks.