Research Tools & Reagents

Liquid chromatography/mass spectrometry (LC/MS) is increasingly being used for metabolic analysis due in part to its widespread availability and compatibility with biological samples. This invention provides ionizable, isotopic labeling reagents and labeling reaction products, answering the current need for relative quantification using mass spectrometry.

Absolute quantification of an analyte relies upon the addition of an internal standard differing only in its isotopic form. However, it is impractical to add an isotopic standard for every compound when performing more comprehensive metabolic profiling. Relative quantification between samples is more amenable to analyzing broad classes of compounds, and it often provides very useful biological information.

Heavy and light isotopic forms of methylacetimidate have been synthesized and used as labeling reagents for quantification of amine-containing molecules, such as biological samples. Heavy and light isotopic forms of formaldehyde and cholamine have also been synthesized and used independently as labeling reagents for quantification of amine-containing and carboxylic acid-containing molecules, such as these found in biological samples. Advantageously, the labeled end-products are positively charged under normal acidic conditions involving conventional liquid chromatography mass spectrometry (LC/MS) applications.

This invention improves the precision of relative quantification by minimizing or negating errors associated with run-to-run irreproducibility. Such errors can arise from variations in mass spectrometric detection sensitivity, such as those caused by ionization suppression in electrospray, or from retention time differences between runs. The isotopic pair of labeled compounds co-elute within a single run. Therefore, they have identical retention times and are electrosprayed from identical solution conditions.

Dr. van der Donk has developed a screening system for identifying novel antibiotics. The system uses phage display and has been optimized for lantibiotic natural products. The system also has utility for investigating interactions between lantibiotics and other peptides. Lantibiotics have complex structures which make them particularly stable under changing pH and protease exposure as well as possessing the ability to bind to bacterial cell wall targets. This makes them ideal for scaffolds for new antibiotic discovery that can combat the burgeoning problem of antibiotic resistance

Professor M. Cristina White has developed iron-based small molecule catalysts which, in conjunction with hydrogen peroxide, can selectively oxidize aliphatic C-H bonds in complex natural products.

Organic synthetic strategies are typically designed around the use of protecting or activating groups to yield desired products. While the use of these types of groups is well developed and widely used, this approach often generates waste and introduces unwanted complexity into the synthetic sequence. Methods which allow introduction of functionalities without activating or protecting groups can significantly impact synthetic methods. In particular, reactions which can predictively and selectively oxidize isolated, unactivated sp3 C-H bonds in complex substrates are of particular value as they enable introduction of functionalities in the later stages of synthetic sequences.

White has developed catalyst systems which achieve this oxidation of C-H bonds based solely on electronic and steric properties of the bond. With the additional use of carboxylate directing groups, diastereoselective lactonizations can be achieved.

A compelling example of the selective oxidation of a C-H bond is the conversion of the antimalarial compound artemisinin which contains five potential C-H sites for oxidation and a cleavage-sensitive peroxide functional group[1]. Using White's iron-based catalyst and its designed selectivity, the targeted C-H bond is oxidized preferentially to give the desired product in higher yields, with shorter reaction times, and in higher volume throughputs compared to enzymatic reactions.

White's catalyst systems open powerful methods to greatly streamline synthetic methods by offering predictive and selective aliphatic C-H oxidation in complex substrates.

Applications

• Pharmaceuticals
• Specialty Chemicals

Benefits

• Predictive and selective oxidation of C-H bonds in complex systems
• Preparatively high yields and rapid reaction rates
• Elimination of need for activating and protecting groups
• Utilization of inexpensive and environmentally friendly oxidant, H202
• Enabling of late-stage introduction of oxidized functionalities

Dr. Kuhlman from the University of Illinois at Urbana-Champaign has created a new system that provides a single editing tool for a variety of genome modifications. This method has the advantage over CRISPR-Cas9 system in not requiring prior modification of the genome and requires only locus-specific primers for genome editing.

This technology is an optimized Landing Pad system that can use positive and negative selection to select for insertion, deletion, and knockout events at genomic targets using specific primers contain homology region A, B, and C. This approach provides a powerful tool for manipulating the genome.

Benefits

• The Landing-Pad system can integrate large fragments of DNA, can be targeted anywhere in the genome and ab be applicable to deletions and knockouts as well.
• Unlike the CRISPR-Cas9 system, this technique does not require a special promoter for gene expression.
• The Landing-Pad system can target different loci with only locus-specific primer design.