Biosynthesis of an amphiphilic silk-like polymer.
An amphiphilic silk-like protein polymer was efficiently produced in the yeast Pichia pastoris. The secreted product was fully intact and was purified by solubilization in formic acid and subsequent precipitation of denatured host proteins upon dilution with water. In aqueous alkaline solution, the negatively charged acidic polymer assumed extended helical (silk III-like) and unordered conformations. Upon subsequent drying, it assumed a conformation rich in beta-turns. In water at low pH, the uncharged polymer aggregated and the solution became turbid. Concentrated solutions in 70% (v/v) formic acid slowly formed gels. Replacement of the formic acid-water mixture with methanol and subsequent drying resulted in beta-sheets, which stacked into fibril-like structures. The novel polymer instantaneously lowered the air-water interfacial tension under neutral to alkaline conditions and reversed the polarity of hydrophobic and hydrophilic solid surfaces upon adsorption.
Werten
Marc W T
MW
Agrotechnology & Food Innovations BV, Wageningen UR, Bornsesteeg 59, NL-6708 PD Wageningen, The Netherlands. marc.werten@wur.nl
Moers
Antoine P H A
AP
Vong
Tuha
T
Zuilhof
Han
H
van Hest
Jan C M
JC
de Wolf
Frits A
FA
D000327:Adsorption; D001704:Biopolymers / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D005656:Fungal Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D044367:Phase Transition; D010843:Pichia; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D012997:Solvents
D001704:Biopolymers; D005656:Fungal Proteins; D011506:Proteins; D012997:Solvents