BIOCHEMISTRY - Textbook - Ostapchenko L. I. - 2012

Chapter 5. STRUCTURE, PROPERTIES AND FUNCTIONS OF PROTEINS

Living Cells synthesize numerous organic molecules, among which polymeric macromolecules—Proteins, Nucleic Acids, and Polysaccharides—play the primary role.

Proteins, also known as proteins (from the Greek proteios, meaning "primary"), play a special role in the vital activity of living organisms. They are characterized by A wide variety of Functions: for instance, enzyme proteins accelerate Chemical Reactions, participate in The transport of cations and anions, contribute to cellular defense reactions, and mediate signal transmission between cells, among other functions.

Proteins account for over 50% of the dry weight within a Cell. The Human Body contains approximately 50,000 individual proteins. The species and individual Specificity of the protein Complement in a given Organism determines the features of its Structure and functioning. In Cells of the same organism undergoing differentiation, the specific set of proteins determines the morphological and Functional Characteristics of each cell type.

Like any polymer, a protein consists of monomeric units, or "building blocks." In human proteins, these monomers are 20 of the several hundred Amino Acids known in nature. The amino acids found in proteins are linked together by peptide bonds. The linear sequence of amino acids in a protein is unique to each individual protein; the information for this sequence is encoded in the region of the DNA molecule known as The Genome.

Through intramolecular interactions, polypeptide chains form spatial structures known as protein Conformations. In a specific region of the protein molecule, amino acid side chains form an Active Site capable of binding specifically (complementarily) to Ligand molecules. The interaction of proteins with ligands forms The basis of their functioning. Alterations in the Amino Acid Sequence of proteins can lead to changes in their spatial STRUCTURE AND FUNCTIONS, potentially triggering The Development of diseases.