1. NAD-dependent formate dehydrogenase was isolated from gram-negative methylotrophic bacteria, strain 1, grown on methanol. The purification procedure involved ammonium sulfate fractionation, ion-exchange chromatography and preparative isotachophoresis or gel filtration ; it resulted in a yield of 40 %.2. The final enzyme preparations were homogeneous as judged by sedimentation in an ultracentrifuge. Formate dehydrogenase purified in the presence of EDTA reveals two bands on electrophoresis in polyacrylamide gel both after protein and activity staining. Two components are transformed into a single one after prolonged storage in the presence of 2-mercaptoethanol.3 . Formate dehydrogenase is a dimer composed of identical or very similar subunits. The molecular weight of the enzyme is about 80000.4. Amino acid composition and some other physico-chemical properties of the enzyme were studied.5. Formate dehydrogenase is specific for formate and NAD as electron acceptor. The Michaelis constant was 0.1 1 mM for NAD and 15 mM for formate (pH 7.0, 37 "C).6. Formate dehydrogenase was rapidly inactivated in the absence of -SH compounds. The enzyme retained full activity upon storage at ambient temperature in solution for half a year in the presence of 2-mercaptoethanol or EDTA.Dehydrogenases are of great importance for microorganisms when taking part in the redox reactions of various functional groups of organic compounds. The perspective of their use in various biotechnological processes (fine organic synthesis, analysis of different metabolites and energetics) gave rise to the interest in the enzymes involved in the redox reactions. The systematic investigation of the structure, mechanism of action and stability of the enzymes of this class is critical for their development as highly effective bioorganic catalysts.At present close attention is being paid to the problem of the enzymatic oxidation of methanol. The last stage of this process is catalyzed by NAD-dependent formate dehydrogenase, observed in the majority of methylotrophic microorganisms [l -81. Since formate dehydrogenase is a part of multienzyme systems it can be used for a number of practical purposes: for example, for the development of an EKJTW. Formate dehydrogenase (EC 1.2.1.2).NADH regeneration system or for the production of hydrogen from organic fuels, etc. In the recent years the interest in formate dehydrogenase has been promoted also by the study of the metabolism of methylotrophic microorganisms.The practical irreversibility of the reaction of formate oxidation to CO2 enables high degrees of substrate conversion to be achieved. The process offers a number of technological advantages: one of the products of the reaction evolves in gaseous form, also formate does not inhibit conjugated enzyme systems and can be easily separated from the end products.The isolation of a strain of methylotrophic bacteria which was an active producer of NAD-dependent formate dehydrogenase [9], enabled us to develop an effective method of purification of this enzyme a...

Exactly 50 years ago, the first article on electrochromism was published. Today electrochromic materials are highly popular in various devices. Interest in nanostructured electrochromic and nanocomposite organic/inorganic nanostructured electrochromic materials has increased in the last decade. These materials can enhance the electrochemical and electrochromic properties of devices related to them. This article describes electrochromic materials, proposes their classification and systematization for organic inorganic and nanostructured electrochromic materials, identifies their advantages and shortcomings, analyzes current tendencies in the development of nanomaterials used in electrochromic coatings (films) and their practical use in various optical devices for protection from light radiation, in particular, their use as light filters and light modulators for optoelectronic devices, as well as methods for their preparation. The modern technologies of “Smart Windows”, which are based on chromogenic materials and liquid crystals, are analyzed, and their advantages and disadvantages are also given. Various types of chromogenic materials are presented, examples of which include photochromic, thermochromic and gasochromic materials, as well as the main physical effects affecting changes in their optical properties. Additionally, this study describes electrochromic technologies based on WO3 films prepared by different methods, such as electrochemical deposition, magnetron sputtering, spray pyrolysis, sol–gel, etc. An example of an electrochromic “Smart Window” based on WO3 is shown in the article. A modern analysis of electrochromic devices based on nanostructured materials used in various applications is presented. The paper discusses the causes of internal and external size effects in the process of modifying WO3 electrochromic films using nanomaterials, in particular, GO/rGO nanomaterials.

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