Synthesis of a reaction intermediate analogue of biotin-dependent carboxylases via a selective derivatization of biotin.

[formula: see text] An efficient and practical synthesis of 1, a unique reaction intermediate analogue of biotin-dependent carboxylases, is described. The synthesis features a selective acylation of the 1'-N of biotin. Target 1 inhibits the activity of the biotin carboxylase component of acetyl CoA carboxylase. It is the first known biotin-derived inhibitor of biotin carboxylase and should promote new kinetic and structural studies of the biotin-dependent carboxylases.

Simple and rapid visual sensing of saccharides.

Solutions of compound 1 exhibit dramatic, characteristic color changes in response to sugar analytes. Structurally related saccharides including glucose phosphates and amino and carboxylic acid sugars can be readily distinguished by visual inspection. These findings should promote the design of unique color sensory materials based on readily available, functional macrocyclic hosts.

Solid-state supramolecular structures of resorcinol-arylboronic acid compounds.

[structure: see text] An X-ray crystallographic study of unique hydrogen-bonded supramolecular solid-state networks comprised of a tetraarylboronic acid resorcinarene is described. When 1 is recrystallized from 9:1 MeOH:EtOH, partial esterification takes place to give compound 2, the corresponding half methyl ester, which forms an infinite two-dimensional array. Each molecule participates in 12 hydrogen bonds with other macrocycles. These hydrogen bonds are both B-OH- - - OH (phenolic) and OH (phenolic)- - -OH (phenolic).

Space-group revision for 4-formylphenylboronic acid.

The space group of the title compound, C7H7BO3, previously reported to be P1, is properly Cc. There is no disorder of the formyl group or in the H atoms of the B(OH)2 group. Molecules lie on approximate twofold axes and are related by approximate centers, which relate all but the formyl O atom and boronic acid H atoms. The B-O distances are 1.363 (2) and 1.370 (2) A.

Vectorially oriented membrane protein monolayers: profile structures via x-ray interferometry/holography.

X-ray interferometry/holography was applied to meridional x-ray diffraction data to determine uniquely the profile structures of a single monolayer of an integral membrane protein and a peripheral membrane protein, each tethered to the surface of a solid inorganic substrate. Bifunctional, organic self-assembled monolayers (SAMs) were utilized to tether the proteins to the surface of Ge/Si multilayer substrates, fabricated by molecular beam epitaxy, to facilitate the interferometric/holographic x-ray structure determination. The peripheral membrane protein yeast cytochrome c was covalently tethered to the surface of a sulfhydryl-terminated 11-siloxyundecanethiol SAM via a disulfide linkage with residue 102. The detergent-solubilized, photosynthetic reaction center integral membrane protein was electrostatically tethered to the surface of an analogous amine-terminated SAM. Optical absorption measurements performed on these two tethered protein monolayer systems were consistent with the x-ray diffraction results indicating the reversible formation of densely packed single monolayers of each fully functional membrane protein on the surface of the respective SAM. The importance of utilizing the organic self-assembled monolayers (as opposed to Langmuir-Blodgett) lies in their ability to tether specifically both soluble peripheral membrane proteins and detergent-solubilized integral membrane proteins. The vectorial orientations of the cytochrome c and the reaction center molecules were readily distinguishable in the profile structure of each monolayer at a spatial resolution of 7 A.