title: Influence of acylation on the adsorption of insulin to hydrophobic surfaces.
abstract: OBJECTIVE
  To study the effect of acylation on the adsorption of insulin to hydrophobic polystyrene beads.
  
  
  METHODS
  Adsorption isotherms for adsorption of insulin and acylated insulin to hydrophobic polystyrene beads were established, and the adsorption of the two proteins was compared further with isothermal titration calorimetry. In addition, the secondary structure and the association behavior of the two proteins were studied with circular dichroism.
  
  
  RESULTS
  Insulin and acylated insulin adsorbed with high affinity to the hydrophobic polystyrene beads. More acylated insulin molecules than insulin molecules adsorbed per unit surface area from solutions containing monomer-dimer mixtures of acylated insulin and insulin, respectively. In contrast, no difference was observed in the number of insulin and acylated insulin molecules adsorbing per unit surface area, when adsorption occurred from solutions containing monomer-dimer-hexamer mixtures.
  
  
  CONCLUSIONS
  The influence of acylation on the adsorption behavior of insulin depends on the association degree of insulin, possibly due to a greater difference in hydrophobicity between monomeric insulin and acylated insulin than between the hexameric forms of these two proteins.
authors.affiliation: Department of Pharmaceutics and Analytical Chemistry Faculty of Pharmaceutical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark. cp@farma.ku.dk
authors.forename: Charlotte
authors.initials: C
authors.lastname: Pinholt
authors.forename: Susanne
authors.initials: S
authors.lastname: Hostrup
authors.forename: Jens Thostrup
authors.initials: JT
authors.lastname: Bukrinsky
authors.forename: Sven
authors.initials: S
authors.lastname: Frokjaer
authors.forename: Lene
authors.initials: L
authors.lastname: Jorgensen
mesh_terms: D000327:Adsorption; D000595:Amino Acid Sequence; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007328:Insulin / Q000737:chemistry*; D008969:Molecular Sequence Data; D013499:Surface Properties
chemical_list: D007328:Insulin