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Biofluids Studied by NMR Spectroscopy*
Biofluids Studied by NMR Spectroscopy John C Lindon, Imperial College London, South Kensington, London, UK & 2010 Elsevier Ltd. All rights reserved. This article is reproduced from the previous edition, volume 1, pp 98–116, & 1999, Elsevier Ltd., with revisions made by the Editor.
Abbreviations AD ADPKD BSA CE CEC CSF CyA DETOCSY HD HDL IDL JRES LDL MACT NAG OA PC PCA PD PR RA SF TE TMAO VLDL
Alzheimer’s disease Autosomal-dominant polycystic kidney disease bovine serum albumin capillary electrophoresis capillary electrochromatography cerebrospinal fluid cyclosporin A diffusion edited TOCSY hemodialysis high-density lipoprotein intermediate-density lipoprotein J-resolved low-density lipoprotein methylacetoacetyl-CoA thiolase N-acetyl glucosaminidase osteoarthritis principal components principal components analysis peritoneal dialysis pattern recognition rheumatoid arthritis synovial fluid traumatic effusions trimethylamine-N-oxide very low density lipoprotein
Introduction Investigation of biofluid composition provides insight into the status of a living organism in that the composition of a particular fluid carries biochemical information on many of the modes and severity of organ dysfunction. One of the most successful approaches to biofluid analysis has been the application of NMR spectroscopy. Thus, NMR spectroscopy of biofluids is a cornerstone of metabonomics that along with proteomics, transcriptomics and genomics forms the basis of systems biology, the current approach to providing a holistic understanding of biochemical changes that occur in disease and as a function of diet, lifestyle and other environmental influences.
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The complete assignment of the 1H NMR spectrum of most biofluids is not possible owing to the enormous complexity of the matrix. However, the assignment problems vary considerably between biofluid types. For instance, seminal fluid and blood plasma are highly regulated with respect to metabolite composition and concentrations, and the majority of the NMR signals have been assigned at 600 and 750 MHz for normal human individuals. Urine composition is much more variable because it is normally adjusted by the body in order to maintain homeostasis, and hence complete analysis is much more difficult. There is also enormous variation in the concentration range of NMR-detectable metabolites in urine samples. With every new increase in available spectrometer frequency, the number of resonances that can be resolved in a biofluid increases, and although this has the effect of solving some assignment problems, it also poses new ones. Furthermore, problems of spectral interpretation arise due to compartmentation and binding of small molecules in the organized macromolecular domains that exist in some biofluids such as blood plasma and bile. All biological fluids have their own characteristic physicochemical properties, and a summary of some of these is given in Table 1 for normal biofluids. These partly dictate the types of NMR experiment that may be employed to extract the biochemical information from each fluid type. An illustration of the complexity of biofluid spectra, and hence the need for ultrahigh field measurements, is given in Figure 1, which shows 800 MHz 1 H NMR spectra of normal human urine, bile, and blood plasma. It is clear that even at the present level of technology in NMR, it is not yet possible to detect many important biochemical substances in body fluids, for example, hormones, because of problems with sensitivity, dispersion, and dynamic range, and this area of research will continue to be technology limited. With this in mind, it would seem prudent to interpret quantitative 1H NMR measurements of intact biological materials and assignment of resonances in 1D spectra with considerable caution even when measured at ultrahigh field. This article thus surveys the various metabolites that have been detected by NMR spectroscopy in a variety of biofluids and provides information on the methods used for identifying them. A comprehensive list of these metabolites and their NMR parameters is given.
Abbreviations AD ADPKD BSA CE CEC CSF CyA DETOCSY HD HDL IDL JRES LDL MACT NAG OA PC PCA PD PR RA SF TE TMAO VLDL
Alzheimer’s disease Autosomal-dominant polycystic kidney disease bovine serum albumin capillary electrophoresis capillary electrochromatography cerebrospinal fluid cyclosporin A diffusion edited TOCSY hemodialysis high-density lipoprotein intermediate-density lipoprotein J-resolved low-density lipoprotein methylacetoacetyl-CoA thiolase N-acetyl glucosaminidase osteoarthritis principal components principal components analysis peritoneal dialysis pattern recognition rheumatoid arthritis synovial fluid traumatic effusions trimethylamine-N-oxide very low density lipoprotein
Introduction Investigation of biofluid composition provides insight into the status of a living organism in that the composition of a particular fluid carries biochemical information on many of the modes and severity of organ dysfunction. One of the most successful approaches to biofluid analysis has been the application of NMR spectroscopy. Thus, NMR spectroscopy of biofluids is a cornerstone of metabonomics that along with proteomics, transcriptomics and genomics forms the basis of systems biology, the current approach to providing a holistic understanding of biochemical changes that occur in disease and as a function of diet, lifestyle and other environmental influences.
128
The complete assignment of the 1H NMR spectrum of most biofluids is not possible owing to the enormous complexity of the matrix. However, the assignment problems vary considerably between biofluid types. For instance, seminal fluid and blood plasma are highly regulated with respect to metabolite composition and concentrations, and the majority of the NMR signals have been assigned at 600 and 750 MHz for normal human individuals. Urine composition is much more variable because it is normally adjusted by the body in order to maintain homeostasis, and hence complete analysis is much more difficult. There is also enormous variation in the concentration range of NMR-detectable metabolites in urine samples. With every new increase in available spectrometer frequency, the number of resonances that can be resolved in a biofluid increases, and although this has the effect of solving some assignment problems, it also poses new ones. Furthermore, problems of spectral interpretation arise due to compartmentation and binding of small molecules in the organized macromolecular domains that exist in some biofluids such as blood plasma and bile. All biological fluids have their own characteristic physicochemical properties, and a summary of some of these is given in Table 1 for normal biofluids. These partly dictate the types of NMR experiment that may be employed to extract the biochemical information from each fluid type. An illustration of the complexity of biofluid spectra, and hence the need for ultrahigh field measurements, is given in Figure 1, which shows 800 MHz 1 H NMR spectra of normal human urine, bile, and blood plasma. It is clear that even at the present level of technology in NMR, it is not yet possible to detect many important biochemical substances in body fluids, for example, hormones, because of problems with sensitivity, dispersion, and dynamic range, and this area of research will continue to be technology limited. With this in mind, it would seem prudent to interpret quantitative 1H NMR measurements of intact biological materials and assignment of resonances in 1D spectra with considerable caution even when measured at ultrahigh field. This article thus surveys the various metabolites that have been detected by NMR spectroscopy in a variety of biofluids and provides information on the methods used for identifying them. A comprehensive list of these metabolites and their NMR parameters is given.