Study Of The Interaction Of Drug Molecules With Human Serum Albumin Using Nuclear Magnetic Resonance Spectroscopy

Study of drug-protein interaction is an interesting topic because it can lead tounderstanding the mechanism of the interaction and can provide the information fordrug design. This dissertation investigated the binding of ligands of Ibupofen (IBP)and Salicylate (SAL) with the receptor of human serum albumin (HSA) using NMRtechnique. The discussion was focused on the following three aspects:1. Affinity NMR is a new methodology of screening potential drug moleculesfrom the mixture without prior separation. This method mainly based on thedifference of NMR parameters (such as chemical shift, relaxation rates and diffusioncoefficient et. al.) of free and bound drug molecules. The properties of the binding(number and location., of the binding sites and dissociation constant) can beenderived from the difference of those NMR parameters which could be accuratemeasured. Affinity NMR is expected to have wide applications in drug screening,modification of the drug molecules and redesign. The principal and application ofaffinity NMR in drug research is discussed in Chapter Two.2. ~1H NMR chemical shift, relaxation and diffusion coefficient measurementswere carried out to study the influence of pH (from 8.0 to 6.1) on the low affinitybinding of Ibuprofen (IBP), a nonsteroidal anti-inflammatory drug, to human serumalbumin (HSA). The study demonstrated that the binding affinity of IBP to HSAincreases when the solution is lowered below the physiological values. Theincreased binding capacity of IBP to HSA at lower pH is attributed to an increase inthe number of (likely hydrophobic) low affinity binding sites, made available uponHSA base-to-neutral conformation transition. Using a fast reversible and site-independent binding model, the number of binding sites of the IBP-HSA complex,calculated from the relaxation data, was 15±2 at pH 8.0 to 22±1 at pH 6.8 3. Cobinding and competitive binding of ligands to receptor is a common, butless studied, phenomena in biological process. The IBP and SAL competitivebinding and cobinding to HSA using relaxation rate and NOE methods had beeninvestigated.