Substrate (chemistry)

About: Substrate (chemistry) is a research topic. Over the lifetime, 35902 publications have been published within this topic receiving 740722 citations. The topic is also known as: enzyme substrate.

Humus and Enzyme Activity

Abstract: Publisher Summary A level of extracellular enzyme activity exists in soil. Enzymes secreted by living cells during normal cell activity, leaked from extant cells, or released from lysed cells, are short-lived unless they are adsorbed by soil colloids or inglobated by humic molecules. This level of extracellular enzyme activity indicates the biological capacity of the soil for the enzymatic conversion of the substrate, which is independent of the extant microbial activity; it also has an important role in the ecology of microorganisms. The activity of enzymes associated with mineral or organic colloids is one of the various activities contributing to the overall activity of the enzyme in soil. The extraction of humus–enzyme complexes from soil in good yields is obtained with solutions employed in extracting humic substances. The intrinsically high electron density of inorganic colloids masks the enzyme reaction product, while the humus material nonspecifically adsorbs the trapping agent becoming electron-dense. Using the electron probe microanalysis overcomes these problems. The chapter analyzes that if extracellular enzymes are observed in the humified organic matter, the comparison of data from extraction–purification experiments with observations by the electron probe microanalyses may prove useful.

Processing system and method for chemically treating a substrate

Abstract: A processing system and method for chemically treating a substrate, wherein the processing system comprises a temperature controlled chemical treatment chamber, and an independently temperature controlled substrate holder for supporting a substrate for chemical treatment. The substrate holder is thermally insulated from the chemical treatment chamber. The substrate is exposed to a gaseous chemistry, without plasma, under controlled conditions including wall temperature, surface temperature and gas pressure. The chemical treatment of the substrate chemically alters exposed surfaces on the substrate.

D-Amino acid oxidase: new findings.

Abstract: The most recent research on D-amino acid oxidases and D-amino acid metabolism has revealed new, intriguing properties of flavoenzymes and enlighted novel biotechnological uses of this catalyst Concerning the in vivo function of the enzyme, new findings on the physiological role of D-amino acid oxidase point to a detoxifying function of the enzyme in metabolizing exogenous D-amino acids in animals A novel role in modulating the level of D-serine in brain has also been proposed for the enzyme At the molecular level, site-directed mutagenesis studies on the pig kidney D-amino acid oxidase and, more recently, on the enzyme from the yeast Rhodotorula gracilis indicated that the few conserved residues of the active site do not play a role in acid-base catalysis but rather are involved in substrate interactions The three-dimensional structure of the enzyme was recently determined from two different sources: at 25–30 A resolution for DAAO from pig kidney and at 12–18 A resolution for R gracilis The active site can be clearly depicted: the striking absence of essential residues acting in acid-base catalysis and the mode of substrate orientation into the active site, taken together with the results of free-energy correlation studies, clearly support a hydrid transfer type of mechanism in which the orbital steering between the substrate and the isoalloxazine atoms plays a crucial role during catalysis

Coupling of nucleic acids to solid support by photochemical methods

Abstract: A solid support capable of binding a nucleic acid thereto upon suitable irradiation, comprising (a) a solid substrate, (b) a photochemically reactive intercalator compound or other nucleic acid-binding ligands, and (c) divalent radical chemically linking the substrate and the ligand (b). Specifically, a hydroxy group-containing solid substrate such as nitrocellulose paper is linked via a bifunctional reagent such as cyanogen bromide or 1,4-butanedioldiglycidyl ether to an amino-substituted angelicin or psoralen or ethidium bromide which in turn is photochemically linked to a nucleic acid. The resulting immobilized nucleic acid probe is capable of hybridizing with complementary nucleic acid fragments and is thereby useful in diagnostic assays.