Allosteric Sensing of Fatty Acid Binding by NMR: Application to Human Serum Albumin

摘要

Human serum albumin (HSA) serves not only as a physiological Oncotic pressure regulator and a ligand carrier but also as a biomarker for pathologies ranging from ischemia to diabetes. Moreover, HSA is a biopharmaceutical with a growing repertoire of putative clinical applications from hypovolemia to Alzheimer's disease. A key determinant of the physiological, diagnostic, and therapeutic functions of HSA is the amount of long chain fatty acids (LCFAs) bound to HSA. Here, we propose to utilize C-13-oleic acid for the NMR-based assessment of albumin-bound LCFA concentration (CONFA). C-13-Oleic acid primes HSA for a LCFA-dependent allosteric transition that modulates the frequency separation between the two main C-13 NMR, peaks of HSA-bound oleic acid (Delta nu(AB)). On the basis of Delta nu(AB), the overall [C-12-LCFA](Tot)/[HSA](Tot) ratio is reproducibly estimated in a manner that is only minimally sensitive to glycation, albumin concentration, or redox potential, unlike other methods to quantify HSA-bound LCFAs such as the albumin-cobalt binding assay.