Synthesis by deamination reaction and crystal structure at 120 K of (16Z,19E)-18-oxo-N-(pyridin-2-yl)-6,7,9,10-tetrahydro-18H-dibenzo[h,o][1,4,7]trioxacyclohexadecine-17-carboxamide

The title compound, C27H24N2O5, is a product of the deamination reaction from aza-14-crown-4 ether containing the γ-piperidone subunit. The title molecule contains a 16-membered macrocycle with the conformation of the C—O—C—C—O—C—C—O—C polyether chain being t–g (-)–t–t–g (+)–t (t = trans, 180°; g = gauche, ±60°). The dihedral angle between the planes of the benzene rings fused to the aza-14-crown-4-ether moiety is 31.11 (14)°. The cavity size inside the macrocycle is 4.72 Å. The macrocycle is significantly flattened as a result of the extended conjugated system. Steric repulsion between the pyridylcarboxamide fragment and the benzene ring results in a slight deviation of macrocycle from planarity. The structure also features intramolecular hydrogen bonding, which results in a deviation of the angle between the planes of amide and pyridyl groups from planarity: this angle is 16.32 (18)°. In the crystal, the molecules are linked into infinite zigzag chains via intermolecular C—H...π contacts. The chains are bound into layers parallel to (100) by weak intermolecular C—H...O hydrogen bonds.

Characterization of Alanine Dehydrogenase and Its Effect on Streptomyces coelicolorA3(2) Development in Liquid Culture

<i>Streptomyces</i>, the most important group of industrial microorganisms, is harvested in liquid cultures for the production of two-thirds of all clinically relevant secondary metabolites. It is demonstrated here that the growth of <i>Streptomyces coelicolor</i> A3(2) is impacted by the deletion of the alanine dehydrogenase (ALD), an essential enzyme that plays a central role in the carbon and nitrogen metabolism. A long lag-phase growth followed by a slow exponential growth of <i>S. coelicolor</i> due to ALD gene deletion was observed in liquid yeast extract mineral salt culture. The slow lag-phase growth was replaced by the normal wild-type like growth by ALD complementation engineering. The ALD enzyme from <i>S. coelicolor</i> was also heterologously cloned and expressed in <i>Escherichia coli</i> for characterization. The optimum enzyme activity for the oxidative deamination reaction was found at 30°C, pH 9.5 with a catalytic efficiency, k_cat/K_M, of 2.0 ± 0.1 mM^–1 s^–1. The optimum enzyme activity for the reductive amination reaction was found at 30°C, pH 9.0 with a catalytic efficiency, k_cat/K_M, of 1.9 ± 0.1 mM^–1 s^–1.

Aromatic primary monoamine-based fast-response and highly specific fluorescent probes for imaging the biological signaling molecule nitric oxide in living cells and organisms

Two fast-response and highly specific NO fluorescent probes were developed, based on the reductive deamination reaction of p-methoxyaniline with NO in aerobic conditions.

Dynamic hydrogels produced via monoamine oxidase B-catalyzed deamination and aldimine crosslinking for 3D printing

Dynamic hydrogels of amino-containing polysaccharides (or proteins) and benzylamine-difunctionalized PEG were prepared via an oxidative deamination reaction catalyzed by MAO B.

Mechanisms for the deamination reaction of 8-oxoguanine catalyzed by 8-oxoguanine deaminase: A combined QM/MM molecular dynamics study

The deamination reaction of 8-oxoguanine (8-oxoG) catalyzed by 8-oxoguanine deaminase (8-oxoGD) plays a critically important role in the DNA repair activity for oxidative damage. In order to elucidate the complete enzymatic catalysis mechanism at the stages of 8-oxoguanine binding, departure of 2-hydroxy-1H-purine-6,8(7H,9H)-dione from the active site, and formation of 8-oxoxanthine, extensive combined QM(PM3)/MM molecular dynamics simulations have been performed. Computations show that the rate-limiting step corresponds to the nucleophilic attack from zinc-coordinate hydroxide group to free 8-oxoguanine. Through conformational analyses, we demonstrate that Trp115, Trp123 and Leu119 connect to O8@8-oxoguanine with hydrogen bonds, and we suggest that mutations of tryptophan (115 and 123) to histidine or phenylalanine and mutation of leucine (119) to alanine could potentially lead to a mutant with enhanced activity. On this ground, a proton transfer mechanism for the formation of 8-oxoxanthine was further discussed. Both Glu218 and water molecule could be used as proton shuttles, and water molecule plays a major role in proton transfer in substrate. On the other hand, comparative simulations on the deamination of guanine and isocytosine reveal that, for the helping of hydrogen bonds between O8@8-oxoguanine and enzyme, O8@8-oxoguanine is the fastest to be deaminated among the three substrates which are also supported by the experimental kinetic constants.