Investigation of Dynamic Biological Systems Using Direct Injection and Liquid Chromatography Mass Spectrometry

Investigation of Dynamic Biological Systems Using Direct Injection and Liquid Chromatography Mass Spectrometry Adam Clayton Swensen Department of Chemistry and Biochemistry, BYU Doctor of Philosophy In biological systems, small changes can have significant impacts. It is, therefore, very important to be able to identify these changes in order to understand what is occurring in the organism. In many cases, this is not an easy task. Mass spectrometry has proven to be a very useful tool in elucidating biological changes even at a very small scale. Several different mass spectrometry based techniques have been developed to discover and investigate complex biological changes. Some of these techniques, such as proteomics, have been through years of development and have advanced to the point that anyone can complete complex analyses of global protein identification and measurement with relative ease. Other techniques are still developing and still have some ground to cover in terms of experimental outcome and ease of execution. Herein we show improvements we have made in high-throughput high-resolution mass spectrometry based techniques to identify and quantify small molecules that are involved in significant biological changes. To begin, we show that our improved high-resolution mass spectrometry based lipidomics techniques are capable of identifying small changes in diseased states that are associated with inflammation, mitochondrial shape and function, and cancer. With our techniques we have been able to extract, identify, and quantify several thousand unique lipid species from complex samples with confidence. Our initial studies looked at global lipidome profiles of differing tissue types from human and mouse biopsies. This was then adapted to compare the global lipidomes of diseased states against healthy states in asthmatic lung tissue, cigarette smoke treated cells, high fat high sugar (HFHS) stressed animals (with and without additional treatment), and in signaling lipids associated with cell death resistance and growth signaling in pancreatic cancer. As a result of our success with lipidomic method improvement we then adapted our techniques and knowledge for use in elucidating small molecule signaling peptides and oxidation changes in proteins. We were able to show that our improved liquid chromatography mass spectrometry based small molecule assays are capable of identifying and quantifying small peptides and protein modifications that would otherwise be undetectable using traditional techniques. This work resulted in the development of a scalable method to detect and quantify the small iron-regulatory hormone known as hepcidin from a variety of samples such as blood, urine, and cell-culture media. We were also instrumental in evaluating and revising a new ultra-high pressure liquid chromatography (UHPLC) system that allows for better separation of analytes from complex mixtures for identification and quantification. Through these advances we hope to aid researchers and clinicians to enable them to use mass spectrometry to further our knowledge about the small but significant changes that regulate complex biological systems.