Complementarity (in chemistry , molecular biology and genetics ) is the mutual correspondence of molecules of biopolymers or their fragments, ensuring the formation of bonds between spatially complementary (complementary) fragments of molecules or their structural fragments due to supramolecular interactions (formation of hydrogen bonds, hydrophobic interactions, electrostatic interactions of charged functional groups etc.).
The interaction of complementary fragments or biopolymers is not accompanied by the formation of a covalent chemical bond between complementary fragments; however, due to the spatial mutual correspondence of complementary fragments, a number of relatively weak bonds (hydrogen and van der Waals) with a sufficiently large total energy are formed, which leads to the formation of stable molecular complexes.
At the same time, it should be noted that the mechanism of the catalytic activity of enzymes is determined by the complementarity of the enzyme and the transition state or the intermediate product of the catalyzed reaction — and in this case a reversible formation of a chemical bond can occur.
Complementarity of nucleic acids
In the case of nucleic acids , both oligo- and polynucleotides, the nitrogenous bases of nucleotides are capable, due to the formation of hydrogen bonds, to form adenine – thymine (or uracil in RNA ) paired complexes and guanine – cytosine when interacting with nucleic acid chains. This interaction plays a key role in a number of fundamental processes for storing and transmitting genetic information: DNA replication , which ensures the transmission of genetic information during cell division, transcription of DNA into RNA during synthesis of proteins encoded by the DNA of the gene , storage of genetic information in double-stranded DNA damage.
DNA
The principle of complementarity is used in the synthesis of DNA messenger RNA by attaching bases to each other (after the daughter has been divided) opposite T-A (thymine-adenine), G-C (guanine-cytosine), C-G (cytosine-guanine) This strict correspondence explained the pattern discovered by Chargaff. DNA chains are not just parallel to each other, hydrogen bonds are formed between members of the А-Т and Г-Ц pairs, which hold the chains together and ensure the correct arrangement of the monomers. It is through these bonds that DNA is the only molecule capable of self-duplication.
Enzyme Catalysis
Complementary enzyme-substrate binding is a key factor in the mechanism of enzymatic activity and, in contrast to the situations described above with the formation of chemically unbound complexes, it can trigger a chemical reaction — in the case of an enzyme binding to a substrate, complementarity is relatively low, but with high complementarity to the transitional state of the substrate stabilization of this state occurs, which leads to the effect of the catalytic activity of enzymes: such stabilization of ne ehodnogo state equivalent to decreasing the activation energy and, therefore, a sharp increase in the reaction rate.