Diazirine Photoprobes for the Identification of Vancomycin-Binding Proteins.

Vancomycin's interactions with cellular targets drive its antimicrobial activity and also trigger expression of resistance against the antibiotic. Interaction partners for vancomycin have previously been identified using photoaffinity probes, which have proven to be useful tools for exploring vancomycin's interactome. This work seeks to develop diazirine-based vancomycin photoprobes that display enhanced specificity and bear fewer chemical modifications as compared to previous photoprobes. Using proteins fused to vancomycin's main cell-wall target, d-alanyl-d-alanine, we used mass spectrometry to show that these photoprobes specifically label known vancomycin-binding partners within minutes. In a complementary approach, we developed a Western-blot strategy targeting the vancomycin adduct of the photoprobes, eliminating the need for affinity tags and simplifying the analysis of photolabeling reactions. Together, the probes and identification strategy provide a novel and streamlined pipeline for identifying vancomycin-binding proteins.

Novel Diazirine Photoprobes for the Identification of Vancomycin-Binding Proteins.

Vancomycin's interactions with cellular targets drive its antimicrobial activity, and also trigger expression of resistance against the antibiotic. Interaction partners for vancomycin have previously been identified using photoaffinity probes, which have proven to be useful tools for exploring vancomycin's interactome. This work seeks to develop diazirine-based vancomycin photoprobes that display enhanced specificity and bear fewer chemical modifications, as compared to previous photoprobes. Using proteins fused to vancomycin's main cell-wall target, D-alanyl-D-alanine, we use mass spectrometry to show that these photoprobes specifically label known vancomycin-binding partners within minutes. In a complementary approach, we developed a Western-blot strategy targeting the vancomycin adduct of the photoprobes, eliminating the need for affinity tags and simplifying the analysis of photolabeling reactions. Together, the probes and identification strategy provide a novel and streamlined pipeline for identifying novel vancomycin-binding proteins.

Optimization of Biocompatibility for a Hydrophilic Biological Molecule Encapsulation System.

Despite considerable advances in recent years, challenges in delivery and storage of biological drugs persist and may delay or prohibit their clinical application. Though nanoparticle-based approaches for small molecule drug encapsulation are mature, encapsulation of proteins remains problematic due to destabilization of the protein. Reverse micelles composed of decylmonoacyl glycerol (10MAG) and lauryldimethylamino-N-oxide (LDAO) in low-viscosity alkanes have been shown to preserve the structure and stability of a wide range of biological macromolecules. Here, we present a first step on developing this system as a future platform for storage and delivery of biological drugs by replacing the non-biocompatible alkane solvent with solvents currently used in small molecule delivery systems. Using a novel screening approach, we performed a comprehensive evaluation of the 10MAG/LDAO system using two preparation methods across seven biocompatible solvents with analysis of toxicity and encapsulation efficiency for each solvent. By using an inexpensive hydrophilic small molecule to test a wide range of conditions, we identify optimal solvent properties for further development. We validate the predictions from this screen with preliminary protein encapsulation tests. The insight provided lays the foundation for further development of this system toward long-term room-temperature storage of biologics or toward water-in-oil-in-water biologic delivery systems.