Browsing by Author "Färber-Schwarz, Aline"

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    Serum albumin and its interaction with the neonatal Fc receptor (FcRn) : characterization of the albumin/FcRn-binding mechanism
    (2013) Färber-Schwarz, Aline; Kontermann, Roland (Prof. Dr.)
    In the past a lot of different biomolecular therapeutics were developed. A common problem using small molecules in therapy is their reduced serum concentration after short time period. The human body clears therapeutic molecules which have a size beneath the kidney clearance threshold in minutes to hours. The consequences are more frequent and high application doses. These facts demand the development of half-life prolonging strategies. plasma proteins, like IgG’s and albumin are recycled by the neonatal Fc receptor (FcRn) resulting in an extraordinary long circulating half-life which is used to prolong the serum circulation of small therapeutic proteins. Non-covalent binding or fusion to the Fc-part of IgG’s or albumin significantly improves the pharmacokinetic properties of small proteins. The aim of this study was to understand the interaction mechanism between albumin and the FcRn and to investigate the impact of point-mutations on the pharmacokinetic properties of albumin. A set of mouse serum albumin (MSA) mutants was generated and their pharmacokinetics were analyzed in vivo. Mutations of H464, E501, E505, D512, H510, S511, E531, H535, D565, T570 and E571 affect the in vivo half-life of albumin in mice. Even if these results are statistically not significant they still suggest the importance of the investigated amino acid residues for the albumin/FcRn binding. The highly conserved histidine residues H464, H510 and H535 play a major role in the albumin/FcRn interaction. In addition to the in vivo experiments a steered molecular dynamic (SMD) visualizes that the domain III of albumin removes as the last part of the protein from the receptor. Furthermore, the polar interactions beween MSA and the mouse FcRn were analyzed. Thus the amino acids S111 and L112 within the domain I and the amino acids E425, L466, T467 and P468 within the domain III of albumin were identified to be responsible for the FcRn interaction. Moreover, phage display was used to mature the affinity of MSA towards the mouse FcRn. A MSA library has been generated by site directed mutagenesis of five amino acids within the domain III of albumin. The selection of MSA variants with an increased affinity to the FcRn was not successful. Further approaches are required to mature the affinity of MSA towards the mouse FcRn.