Basil glands of the Sweet Dani cultivar contain high levels of citral, a mixture of geranial and its cis-isomer neral, as well as low levels of geraniol and nerol. We have previously reported the identification of a cDNA from Sweet Dani that encodes an enzyme responsible for the formation of geraniol from geranyl diphosphate in the glands, and that these glands cannot synthesize nerol directly ...

4-Oxalocrotonate tautomerase (4-OT) catalyzes the enol-keto tautomerization of 2-hydroxymuconate, utilizing its N-terminal proline (Pro-1) as general base catalyst. Substituting Pro-1 with bulky or charged residues will result in poor or no post-translational removal of the translation-initiating methionine by the methionine aminopeptidase (MetAP) of the Escherichia coli expression host. Here, ...

The chemical locking of the central single bond in core chromophores of green fluorescent proteins (GFPs) influences their excited-state behavior in a distinct manner. Experimentally, it significantly enhances the fluorescence quantum yield of GFP chromophores with an ortho-hydroxyl group, while it has almost no effect on the photophysics of GFP chromophores with a para-hydroxyl group. To unrav...

2,3,7,8,12,13,17,18-Octaethyl-5,15-diphenylporphyrin (1) is characterized by an inner cavity with a rectangular shape and small NH⋅⋅⋅N distances. It resembles porphycene, which is a constitutional isomer of porphyrin known for its strong intramolecular hydrogen bonds and rapid tautomerization. Such distortion of the porphyrin cavity leads to tautomeric properties of 1 that are intermediate betw...

Beta-Ketoadipate enol-lactone hydrolase catalyzes a common step in the utilization of protocatechuate and cis,cis-muconate by bacteria. Either of the two compounds elicits the synthesize of an enol-lactone hydrolase in Acinetobacter. The enol-lactone hydrolase that is induced by each compound was purified, and the properties of the proteins were compared. Both enzymes appear to be dimers with m...

MP2, DFT and CCSD methods with 6-311++G** and aug-cc-pvdz basis sets have been used to probe the structural changes and relative energies of E-prop-2-ynylideneamine (I), Z-prop-2-ynylideneamine (II), prop-1,2-diene-1-imine (III) and vinyl cyanide (IV). The energy near-equivalence and provenance of preference of isomers and tautomers were investigated by NBO calculations using HF and B3LYP metho...

High-level quantum-chemical and quantum-dynamics calculations are reported on the tautomerization equilibria and rate constants of isolated and monohydrated cytosine and guanine molecules. The results are used to estimate the fraction of the bases present in the cell during DNA synthesis as the unwanted tautomers that forms irregular base pairs, thus giving rise to a spontaneous GC→AT point mut...

A concise synthesis of rubioncolin B is described, which features an unprecedented intramolecular Diels-Alder reaction involving an ortho-quinone methide and a naphthofuran moiety. The ortho-quinone methide is generated through a surprisingly facile tautomerization of a para-quinone.

[reaction: see text] The chiral disphosphines with tunable dihedral angles (TunaPhos) have been used for asymmetric hydrogenation of enol acetates and dihedral-angle-dependent enantioselectivities were observed. C2-TunaPhos has been proved to be effective for Ru-catalyzed asymmetric hydrogenation of electron-deficient and other enol acetates.

[reaction: see text] Monodentate phosphoramidites, in particular PipPhos and its octahydro analogue, are excellent ligands for the rhodium-catalyzed asymmetric hydrogenation of aromatic enol acetates, enol carbamates, and 2-dienol carbamates up to 98% ee. These latter substrates were hydrogenated selectively to the carbamates of the allyl alcohol.