title: Adsorption dynamics of L-glutamic acid copolymers at a heptane/water interface.
abstract: Random copolymers of glutamic acid (glu-ala, glu-leu, glu-phe, glu-tyr) were employed to investigate the relationship between side chain structure and peptide charge on adsorption behavior at an oil/water boundary. Adsorption of a series of glutamate copolymers at a heptane/water interface was examined by the dynamic pendant-drop method to determine interfacial tension. Incorporation of leucine or phenylalanine into a glutamate copolymer results in greater tension reduction than incorporation of alanine or tyrosine. These effects are amplified at pH values near the isoelectric point of glutamate, where macroscopic adsorbed films of glu-leu and glu-phe exhibit gel-like properties in response to interfacial area compression. Differences in interfacial tension behavior of glu-tyr and glu-phe indicate the importance of the tyrosine p-hydroxyl group on adsorption and aggregation at the oil/water interface.
authors.affiliation: Department of Chemical Engineering, University of California Berkeley 94720, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Beverung
authors.forename: C J
authors.initials: CJ
authors.lastname: Radke
authors.forename: H W
authors.initials: HW
authors.lastname: Blanch
mesh_terms: D000327:Adsorption; D000409:Alanine / Q000737:chemistry; D002942:Circular Dichroism; D018698:Glutamic Acid / Q000737:chemistry*; D006536:Heptanes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007091:Image Processing, Computer-Assisted; D007526:Isoelectric Point; D007930:Leucine / Q000737:chemistry; D008968:Molecular Conformation; D010649:Phenylalanine / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D013500:Surface Tension; D014443:Tyrosine / Q000737:chemistry
chemical_list: D006536:Heptanes; D011108:Polymers; D018698:Glutamic Acid; D014443:Tyrosine; C028618:n-heptane; D010649:Phenylalanine; D007930:Leucine; D000409:Alanine