Human Serum Albumin Characterisation and Binding Studies by Spectroscopic Techniques
Human Serum Albumin (HSA) is a plasma protein of great significance with an ability to bind numerous endogenous and exogenous ligands, having a single polypeptide chain of 585 amino acids constructed in three domains of relatively equal size. Although HSA's existence has been known for many years, its characterisation and ability to bind ligands still remain enigmatic. Only in 1992 was the crystal structure of HSA reported (Carter and Ho, 1992). Effective crystallisation and the determination of meaningful crystallographic data and structure had proven difficult. The 1992 report concerned HSA crystals grown using zero gravity conditions. The objective of this project is the characterisation of recombinant and native HSA using Ultraviolet (UV) & circular dichroism spectroscopy (CD) and involved HSA conformational changes, which altered the ability to bind or off-load ligands. Changing environment, together with the use of characteristic "marker ligands," influences binding to provide a handle that can be utilised and monitored. This enables the assignment of binding sites and the study of perturbating conditions. Changing conditions such as pH, temperature, ionic strength and solvents in the presence and absence of ligands were employed to extract further information on this elusive protein. Fragments of recombinant HSA were also used (namely domain I and domain I + II) under identical conditions as the whole protein in order to help elucidate and assign binding sites.
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