Biomedical subjects

Jacob M Hooker

Publications and source records attributed to Jacob M Hooker.

3 recordsLinked to original sources

PubMed2007

Solubilization and stabilization of bacteriophage MS2 in organic solvents.

Several techniques were examined for the solubilization of bacteriophage MS2 in organic solvents. Direct extraction of the MS2 from an aqueous phase into isooctane containing 2 mM AOT, a proven approach for the organic solubilization of many proteins, was not successful. However, predried samples of MS2 were solubilized through the direct addition of organic solvents containing 500 mM AOT. As an alternative procedure, reverse micelles containing aqueous solutions of MS2 were prepared in isooctane using AOT, dehydrated through solvent evaporation and azeotropic drying, and resolubilized in a solvent of choice. The structure and microenvironment of organic-solubilized MS2 were investigated by UV absorbance, the fluorescence emission of an attached solvatochromatic dye, tryptophan fluorescence, and atomic force microscopy, all of which contributed evidence for a fully assembled capsid in the organic solvent. The solubilized MS2 was derivatized with stearic acid in chloroform, illustrating that bioconjugation reactions can be performed on organic-solubilized capsids using reagents that are completely insoluble in water. Furthermore, the organic-solubilized phage remained infectious after heating at 90 degrees C for 20 min, whereas phage in aqueous buffer or dried with nitrogen were nonviable following the heat treatment protocol. The extended range of available chemical modifications and the enhanced thermal stability of the organic-solubilized capsids bodes well for the formulation of storage-stable vaccines predicated on reactions in or exposure to organic media.

Biotechnology↗

PubMed2006

Modification of aniline containing proteins using an oxidative coupling strategy.

A new bioconjugation reaction has been developed based on the chemoselective modification of anilines through an oxidative coupling pathway. Aryl amines were installed on the surface of protein substrates through lysine acylation reactions or through the use of native chemical ligation techniques. Upon exposure to NaIO4 in aqueous buffer, the anilines coupled rapidly to the aromatic rings of N,N-dialkyl-N'-acyl-p-phenylenediamines. The identities of the reaction products were confirmed using ESI-MS and through comparison to small molecule analogs. Control experiments indicated that none of the native amino acids participated in the reaction. The resulting bioconjugates were found to be stable toward hydrolysis from pH 4 to pH 11 and in the presence of many commonly used oxidants, reductants, and nucleophiles. A fluorescent phenylenediamine reagent was synthesized for the selective detection of aniline labeled proteins in mixtures, and the reaction was used to append the C-terminus of the green fluorescent protein with a single PEG chain. When combined with techniques for the incorporation of unnatural amino acids into proteins, this bioorthogonal coupling method should prove useful for a number of applications requiring a high degree of labeling specificity.

Aniline Compounds↗

PubMed2004

Interior surface modification of bacteriophage MS2.

An efficient strategy for the interior surface functionalization of MS2 viral capsids is reported, featuring a new hetero-Diels-Alder bioconjugation reaction. After virus isolation, the RNA genome was removed from the spherical particles by exposure to pH 11.8 conditions for a period of 4 h. Following this, 180 tyrosine residues on the interior surface of each "empty" capsid shell were modified by using a site-selective diazonium-coupling reaction. To attach additional functionality, the azo conjugate was reduced with Na2S2O4 to afford an ortho-amino tyrosine derivative. Oxidation of this moiety with NaIO4 produced an o-iminoquinone on the protein surface, which was found to undergo an efficient hetero-Diels-Alder reaction with N-(4-aminophenyl)acrylamide. This four-step procedure can be carried out in under 4 h, reaches high levels of conversion, and yields the desired conjugates in >60% overall yield.

Bioreactors↗