Biomedical subjects

M G Finn

Publications and source records attributed to M G Finn.

42 records · Page 3Linked to original sources

PubMed2001

Desorption/ionization on silicon (DIOS): a diverse mass spectrometry platform for protein characterization.

Since the advent of matrix-assisted laser desorption/ionization and electrospray ionization, mass spectrometry has played an increasingly important role in protein functional characterization, identification, and structural analysis. Expanding this role, desorption/ionization on silicon (DIOS) is a new approach that allows for the analysis of proteins and related small molecules. Despite the absence of matrix, DIOS-MS yields little or no fragmentation and is relatively tolerant of moderate amounts of contaminants commonly found in biological samples. Here, functional assays were performed on an esterase, a glycosidase, a lipase, as well as exo- and endoproteases by using enzyme-specific substrates. Enzyme activity also was monitored in the presence of inhibitors, successfully demonstrating the ability of DIOS to be used as an inhibitor screen. Because DIOS is a matrix-free desorption technique, it also can be used as a platform for multiple analyses to be performed on the same protein. This unique advantage was demonstrated with acetylcholine esterase for qualitative and quantitative characterization and also by its subsequent identification directly from the DIOS platform.

Acetylcholine↗

PubMed2001

Porous silicon as a versatile platform for laser desorption/ionization mass spectrometry.

Desorption/ionization on porous silicon mass spectrometry (DIOS-MS) is a novel method for generating and analyzing gas-phase ions that employs direct laser vaporization. The structure and physicochemical properties of the porous silicon surfaces are crucial to DIOS-MS performance and are controlled by the selection of silicon and the electrochemical etching conditions. Porous silicon generation and DIOS signals were examined as a function of silicon crystal orientation, resistivity, etching solution, etching current density, etching time, and irradiation. Pre-and postetching conditions were also examined for their effect on DIOS signal as were chemical modifications to examine stability with respect to surface oxidation. Pore size and other physical characteristics were examined by scanning electron microscopy and Fourier transform infrared spectroscopy, and correlated with DIOS-MS signal. Porous silicon surfaces optimized for DIOS response were examined for their applicability to quantitative analysis, organic reaction monitoring, post-source decay mass spectrometry, and chromatography.

Journal Article↗

PubMedDate not supplied

Blue fluorescent antibodies as reporters of steric accessibility in virus conjugates.

Nonenveloped viruses provide the chemist with large, preassembled polyvalent protein scaffolds for modification. These structures are typically porous to small molecules but not to large ones. The solution-phase structures and reactivities of such assemblies may be substantially different than indicated by X-ray crystal structures. Here, the attachment of organic compounds to either the inside or outside surface of the cowpea mosaic virus (CPMV) coat protein was verified with an indicating antibody-antigen interaction. Antibody binding was subsequently blocked by the installation of poly(ethylene glycol) chains. These results typify the type of site-specific control that is available with CPMV and related virus building blocks.

Antibodies, Viral↗

PubMedDate not supplied

Accelerated bioorthogonal conjugation: a practical method for the ligation of diverse functional molecules to a polyvalent virus scaffold.

Covalent bond formation to proteins is made difficult by their multiple unprotected functional groups and normally low concentrations. A water-soluble sulfonated bathophenanthroline ligand (2) was used to promote a highly efficient Cu(I)-mediated azide-alkyne cycloaddition (CuAAC) reaction for the chemoselective attachment of biologically relevant molecules to cowpea mosaic virus (CPMV). The ligated substrates included complex sugars, peptides, poly(ethylene oxide) polymers, and the iron carrier protein transferrin, with routine success even for cases that were previously resistant to azide-alkyne coupling using the conventional ligand tris(triazolyl)amine (1). The use of 4-6 equiv of substrate was sufficient to achieve loadings of 60-115 molecules/virion in yields of 60-85%. Although it is sensitive to oxygen, the reliably efficient performance of the Cu.2 system makes it a useful tool for demanding bioconjugation applications.

Carbohydrates↗

PubMedDate not supplied

"Clickable" agarose for affinity chromatography.

Successful purification of biological molecules by affinity chromatography requires the attachment of desired ligands to biocompatible chromatographic supports. The Cu(I)-catalyzed cycloaddition of azides and alkynes-the premier example of "click chemistry"-is an efficient way to make covalent connections among diverse molecules and materials. Both azide and alkyne units are highly selective in their reactivity, being inert to most chemical functionalities and stable to wide ranges of solvent, temperature, and pH. We show that agarose beads bearing alkyne and azide groups can be easily made and are practical precursors to functionalized agarose materials for affinity chromatography.

Alkynes↗

PubMedDate not supplied

Hybrid virus-polymer materials. 1. Synthesis and properties of PEG-decorated cowpea mosaic virus.

Cowpea mosaic virus was derivatized with poly(ethylene glycol) to give well-controlled loadings of polymer on the outer surface of the coat protein assembly. The resulting conjugates displayed altered densities and immunogenicities, consistent with the known chemical and biological properties of PEG. These studies make CPMV potentially useful as a tailored vehicle for drug delivery.

Animals↗