The mammalian O-GlcNAc hydrolase (OGA) removes O-GlcNAc from serine and threonine residues on intracellular glycoproteins. OGA activity is sensitive to N-acyl substitutions to O-GlcNAc, with alkyl diazirine-modified O-GlcNAc (O-GlcNDAz) being completely resistant to removal by OGA. Using homology modeling, we identified OGA residues proximal to the N-acyl position of O-GlcNAc substrate. Mutatio...

Phenotypic screening provides a means to discover small molecules that perturb cell biological processes. Discerning the proteins and biochemical pathways targeted by screening hits, however, remains technically challenging. We recently described the use of small molecules bearing photoreactive groups and latent affinity handles as fully functionalized probes for integrated phenotypic screening...

We introduce the use of a hydroborated polyisoprene (PIP) macroinitiator for the rapid surface-initiated growth of superhydrophobic polymethylene (PM) films. Rinsing of a dip-coated PIP film on a methyl-terminated surface atop silicon or gold substrates results in robustly bound, isolated PIP clusters. After hydroboration of the internal olefins, these clusters result in extremely rapid growth ...

Metal-diazo radicals of α-carbonyl diazomethanes are new members of the radical family and are precursors to metal-carbene radicals. Herein, using electron paramagnetic resonance spectroscopy with spin-trapping, we detect diazo radicals of α-carbonyl diazomethanes, induced by [Rh(I)Cl(cod)]2, [Co(II)(por)] and PdCl2, at room temperature. The unique quintet signal of the Rh-diazo radical was obs...

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Multiphoton ionization and dissociation processes in diazirine have been studied experimentally via 304-325 nm two-photon absorption and theoretically by using the EOM-CCSD and B3LYP methods. The electronic structure calculations identified two excited valence states and four Rydberg states in the region 4.0-8.5 eV. In one-photon excitation, the strongest absorption is to the 2(1)A(1)(3p(x) <--...

1. A new and convenient synthesis of p-nitrophenyl diazoacetate has been devised from p-nitrophenyl chloroformate and diazomethane. 2. p-Nitrophenyl diazoacetate reacts stoichiometrically with chymotrypsin to yield diazoacetyl chymotrypsin. 3. Photolysis of the diazoacetyl enzyme with light of wave length greater than 320 rnp yields a mixture of (a) glycolic acid and regenerated chymotrypsin an...

Photoaffinity labeling is a powerful tool to identify protein targets of biologically active small molecules, yet is often limited by the size, chemical properties, and availability of photoreactive groups. We report an improved synthesis of photo-leucine, a diazirine-based photoreactive analogue of leucine, and demonstrate its incorporation into a cyclodepsipeptide inhibitor of cotranslational...

A novel conformational structure of bilirubin is presented which obtains maximum stabilization through a system of four intramolecular hydrogen bonds. Two hydrogen bonds link oxygen and nitrogen atoms of each end ring to the contralateral carboxyl group. The proposed structure can explain a variety of uncommon features of bilirubin, and reconciles many seemingly contradictory hypotheses by acco...

A number of nonamino organic acids associated with inborn errors of metabolism can be detected by gas chromatography. The organic acids are extracted into ethyl acetate and diethyl ether, the extracts combined, and the solvents evaporated under nitrogen. The residue is taken up in carbon disulfide and an aliquot chromatographed on 5% neopentyl glycol adipate to separate short-chain fatty acids ...