The article analyzes the role of hydrogen bonds and supramolecular structures in enzyme catalysis and model systems. Hydrogen bonds play a crucial role in many enzymatic reactions. However, scientists have only recently attempted to harness the power of hydrogen bonds in homogeneous catalytic systems. One of the newest directions is associated with attempts to control the properties of catalysts by influencing the “second coordination sphere” of metal complexes. The role H-bonding, and the building of stable supramolecular nanostructures due to intermolecular H-bonds, based on catalytic active heteroligand iron (Fe) or nickel (Ni) complexes formed during hydrocarbon oxidations were assessed via the AFM (Atomic-force microscopy) method, which was proposed and applied by authors of this manuscript. Th is article also discusses the roles of hydrogen bonds and supramolecular structures in oxidation reactions catalyzed by heteroligand Ni and Fe complexes, which are not only effective homogeneous catalysts but also structural and functional models of Oxygenases.

A new approach to the research of supramolecular complexes by the AFM method and the possible role of hydrogen bonds in the formation of nanostructures of metal complexes simulating the active centers of enzymes was proposed. The formation of these structures occurs due to non-covalent intermolecular interactions, and to a certain extent reflects the structure of the complexes involved in the mechanisms of homogeneous and enzymatic catalysis, as well as during morphological changes of cells.

The catalytic effects of small amounts of water (∼10⁻³ mol/l) added to the ethylbenzene oxidation reaction with molecular oxygen catalyzed by the system {Fe(III)(acac)₃ + 18-crown-6 (18C6)} were revealed. An increase in the reaction rate was observed, and the direction of the oxidation reaction changed. In the presence of the catalytic system {Fe(III)(acac)₃ (5.0 × 10⁻³ mol/l) + 18C6 (5.0 × 10⁻³ mol/l) + H₂O (3.7 × 10⁻³ mol/l}, the main product at early stages of ethylbenzene oxidation is acetophenone, rather than α-phenylethyl hydroperoxide produced in the case of catalysis by the system {Fe(III)(acac)₃ (5.0 × 10⁻³ mol/l) + 18C6 (5.0 × 10⁻³ mol/l)} (in the absence of water admixture). A method is proposed to evaluate the activity of forming in situ (Fe(II)(acac)₂) _x (18C6) _y (H₂O) _n complexes at microstages of chain initiation (O₂ activation) and propagation (Ct+RO ₂ ^· ) involving the catalyst, which determine the rate and selectivity of oxidation. A possible “dioxygenase-like” mechanism of conversion of iron complexes with 18C6 in the presence of activating H₂O admixtures is discussed.

For the first time AFM (atomic-force microscopy) was used to record significant changes in the geometric parameters of the image of erythrocytes in vitro under conditions of glycolytic starvation (ATP (Adenosine triphosphate) deficiency). The difference in the action of antioxidants, phenosan K, and Ihfan-10 on erythrocytes that we detected with AFM seems to be mainly due to their difference in hydrophobicity. We used the AFM method to research the self-organization of the components of the active center of P450 (Porphyrin-450) metalloenzymes that are part of a class of hemoproteins with functions of affinity to molecular oxygen O₂. Stable supramolecular nanostructures in the form of triangular prisms based on the iron porphyrin complex with amino acids due to self-assembly involving intermolecular hydrogen bonds were received. A possible scheme for the formation of such structures is proposed.

Earlier, we established that nickel or iron heteroligand complexes, which include PhOH (nickel complexes) or tyrosine residue (nickel or iron complexes), are not only hydrocarbon oxidation catalysts (in the case of PhOH), but also simulate the active centers of enzymes (PhOH, tyrosine). The AFM method established the self-organization of nickel or iron heteroligand complexes, which included tyrosine residue or PhOH, into supramolecular structures on a modified silicon surface. Supramolecular structures were formed as a result of H-bonds and other non-covalent intermolecular interactions and, to a certain extent, reflected the structures involved in the mechanisms of reactions of homogeneous and enzymatic catalysis. Using the AFM method, we obtained evidence at the model level in favor of the involvement of the tyrosine fragment as one of the possible regulatory factors in the functioning of Ni(Fe)ARD dioxygenases or monooxygenases of the family of cytochrome P450. The principles of actions of these oxygenases were used to create highly efficient catalytic systems for the oxidation of hydrocarbons.

Background: The AFM-techniques have been used for the research of the role of intermolecular H-bonds and stable supramolecular nanostructures, based on effective catalysts of oxidation processes, which are also models of Ni(Fe)ARD Dioxygenases, in mechanisms of catalysis. Methods and Results: The role of Histidine and Tyrosine ligands in the mechanisms of catalysis by FeARD on model systems is discussed based on AFM and UV-Spectroscopy data. Conclusion: We first offer the new approach – method of atomic force microscopy (AFM) – to study the possibility of the formation of supramolecular nanostructures, and also for assessing of role the intermolecular hydrogen bonds (and the other intermolecular non-covalent interactions) in mechanisms of homogeneous and enzymatic catalysis with nickel and iron complexes.