Introduction

Abstract

Since the completion of the first whole genome sequence, that of the microorganism Haemophilus influenzae (Fleischmann et al., 1995), we have increasingly realized the paucity of our knowledge with respect to the function of novel genes. The completion of draft sequences for the human genome has accelerated demand for determining the biochemical function of orphan genes and for validating them as molecular targets for therapeutic intervention. The search for biomarkers that can serve as indicators of disease progression or response to therapeutic intervention has also increased. Functional analyses have emphasized gene expression studies (transcriptomics) and protein profiling (proteomics). Considerably less emphasis has been placed on profiling the end products of gene expression, the metabolome. To date, the use of metabolite analyses as a tool in describing biochemical networks has been aimed primarily at accurate quantitation of substrates and products in an individual enzymatic pathway. There has, however, been an increasing emphasis on producing spectral “fingerprints” of metabolic profiles that can be correlated to a phenotype of interest without identification of specific metabolite classes. Further, by parallel analytical testing of sample tissues or biofluids a number of chemically different metabolites can be readily identified and quantitated.