This proposal requests funds for a high-performance liquid chromatograph (HPLC) that is suitable for both analytical and preparative work, as a major instrumentation supplement in support of the parent grant R01GM125669, Mechanism of Microbial DNA Hypervariation through Mutagenic Transposition. A highcaliber HPLC is a critical piece of standard laboratory equipment for almost any cutting edge biochemical research. This instrument will be used in preparative capacity for purification of chemically-modified oligonucleotides (such as dye-labeled primers and site-specifically modified DGR cDNA intermediates), proteins (such as bRT and bAvd from Bordatella phage and from phylogenetically related phage), and specialty small molecules (such as modified nucleotide analogs). We would also use the instrument in analytical capacity for quantitative assessment of chemical purity of reaction products involving small molecules, macromolecules, and conjugated variants of the macromolecules.