Optimizing the Readout of Lanthanide-DOTA Complexes for the Detection of Ligand-Bound Copper(I).

The CuAAC 'click' reaction was used to couple alkyne-functionalized lanthanide-DOTA complexes to a range of fluorescent antennae. Screening of the antenna components was aided by comparison of the luminescent output of the resultant sensors using data normalized to account for reaction conversion as assessed by IR. A maximum 82-fold enhanced signal:background luminescence output was achieved using a Eu(III)-DOTA complex coupled to a coumarin-azide, in a reaction which is specific to the presence of copper(I).

Exploring the substrate specificity of OxyB, a phenol coupling P450 enzyme involved in vancomycin biosynthesis.

OxyB is a cytochrome P450 enzyme that catalyzes the first oxidative phenol coupling reaction during vancomycin biosynthesis. The preferred substrate is a linear peptide linked as a C-terminal thioester to a peptide carrier protein (PCP) domain of the glycopeptide antibiotic non-ribosomal peptide synthetase. Previous studies have shown that OxyB can efficiently oxidize a model hexapeptide-PCP conjugate (R-Leu(1)-R-Tyr(2)-S-Asn(3)-R-Hpg(4)-R-Hpg(5)-S-Tyr(6)-S-PCP) (Hpg = 4-hydroxyphenylglycine) into a macrocyclic product by phenolic coupling of the aromatic rings in residues-4 and -6.

Contribution of the mevalonate and methylerythritol phosphate pathways to the biosynthesis of dolichols in plants.

Plant isoprenoids are derived from two biosynthetic pathways, the cytoplasmic mevalonate (MVA) and the plastidial methylerythritol phosphate (MEP) pathway. In this study their respective contributions toward formation of dolichols in Coluria geoides hairy root culture were estimated using in vivo labeling with (13)C-labeled glucose as a general precursor. NMR and mass spectrometry showed that both the MVA and MEP pathways were the sources of isopentenyl diphosphate incorporated into polyisoprenoid chains.

Enabling methodology for the end functionalization of glycosaminoglycan oligosaccharides.

The chemical functionalization of glycosaminoglycans is very challenging due to their structural heterogeneity and polyanionic character; but as an enabling technology it promises rich rewards in terms of the structural and biological data it will afford. This review surveys the known methods for the preparation of glycosaminoglycan oligosaccharides and conditions for the selective functionalization of both the reducing and non-reducing ends. The synthetic merits of each approach are discussed, together with the structural modification of the glycosaminoglycan oligosaccharide which they confer.

Oxidative phenol coupling reactions catalyzed by OxyB: a cytochrome P450 from the vancomycin producing organism. implications for vancomycin biosynthesis.

OxyB is a cytochrome P450 enzyme that catalyzes the first phenol coupling reaction during the biosynthesis of vancomycin-like glycopeptide antibiotics. The phenol coupling reaction occurs on a linear peptide intermediate linked as a C-terminal thioester to a peptide carrier protein (PCP) domain within the multidomain glycopeptide nonribosomal peptide synthetase (NRPS). Using model peptides with the sequence (R)(NMe)Leu-(R)Tyr-(S)Asn-(R)Hpg-(R)Hpg-(S)Tyr-S-PCP and (R)(NMe)Leu-(R)Tyr-(S)Asn-(R)Hpg-(R)Hpg-(S)Tyr-(S)Dpg-S-PCP (where Hpg = 4-hydroxyphenylglycine, and Dpg = 3,5-dihydroxyphenylglycine), or containing (R)Leu instead of (R)(NMe)Leu, attached to recombinant PCPs derived from modules-6 and -7 in the vancomycin NRPS, we show that cross-linking of Hpg4 and Tyr6 by OxyB can occur in both hexapeptide- and heptapeptide-PCP conjugates.

Lewis acid mediated regioselective ring opening of benzylglycidol with dibenzyl phosphate: Short and attractive synthesis of dihydroxyacetone phosphate.

A novel, mild, and efficient method was described to introduce a dibenzyl phosphate by ring opening of benzylglycidol mediated by Lewis acids. This methodology was used as a key step for synthesizing the dihydroxyacetone phosphate (DHAP) in only three steps with an overall yield of 74% from the commercially available racemic benzylglycidol.

Isoprenoid biosynthesis via the MEP pathway. Synthesis of (3,4)-3,4-dihydroxy-5-oxohexylphosphonic acid, an isosteric analogue of 1-deoxy-D-xylulose 5-phosphate, the substrate of the 1-deoxy-D-xylulose 5-phosphate reducto-isomerase.

(3,4)-3,4-Dihydroxy-5-oxohexylphosphonic acid, an isosteric analogue of 1-deoxy-D-xylulose 5-phosphate (DXP), was obtained in enantiomerically pure form from (+)-2,3--benzylidene--threitol by a seven-step sequence. This phosphonate did not affect the growth of. It did not inhibit the 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), but was converted by this enzyme into (3,4)-3,4,5-trihydroxy-3-methylpentylphosphonic acid, an isosteric analogue of 2-C-methyl-D-erythritol 4-phosphate.

Cross-talk between the cytosolic mevalonate and the plastidial methylerythritol phosphate pathways in tobacco bright yellow-2 cells.

In plants, two pathways are utilized for the synthesis of isopentenyl diphosphate, the universal precursor for isoprenoid biosynthesis. The key enzyme of the cytoplasmic mevalonic acid (MVA) pathway is 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR). Treatment of Tobacco Bright Yellow-2 (TBY-2) cells by the HMGR-specific inhibitor mevinolin led to growth reduction and induction of apparent HMGR activity, in parallel to an increase in protein representing two HMGR isozymes.