A pH-responsive interface derived from resilin-mimetic protein Rec1-resilin.
In this investigation, for the first time we report the effects of pH on the molecular orientation, packing density, structural properties, adsorption characteristics and viscoelastic behaviour of resilin-mimetic protein rec1-resilin at the solid-liquid interface using quartz crystal microbalance with dissipation monitoring (QCM-D) and surface plasmon resonance (SPR) spectroscopy. QCM-D and SPR data confirm that the binding ability of rec1-resilin on a substrate is strongly pH-dependent the protein packing density on a gold surface is calculated to be 4.45 x 10(13) per cm(2) at the isoelectric point (IEP approximately 4.9), 8.79 x 10(11) per cm(2) at pH 2 and 9.90 x 10(11) per cm(2) at pH 12, respectively. Our findings based on the thickness, dissipation and viscoelasticity of the rec1-resilin adlayer also indicate that it is adsorbed onto the gold substrate with different orientation depending on pH, such as back-on adsorption at acidic pH of 2, compact end-on bilayer adsorption at the IEP and side-on at high alkaline pH of 12. When rec1-resilin is 'pinned' to the substrate at IEP and subsequently exposed to an electrolyte solution adjusted to different pH, it switches from a compact globular conformation of the bio-macromolecule at the IEP to a coil conformation at pH between IEP to IED (IED = pKa value of tyrosine amino acid residue) and an extended coil conformation at pH > IED. This transformation from globule to coil to extended coil conformation is kinetically fast, robust and completely reversible. Such responsive surfaces created using 'smart' biomimetic rec1-resilin have the potential to find applications in many areas including biotechnology, medicine, sensors, controlled drug delivery systems and engineering.
Truong
My Y
MY
Ian Wark Research Institute, ARC Special Research Centre, Mawson Lakes Campus, University of South Australia, Mawson Lakes, SA 5095, Australia.
Dutta
Naba K
NK
Choudhury
Namita R
NR
Kim
Misook
M
Elvin
Christopher M
CM
Hill
Anita J
AJ
Thierry
Benjamin
B
Vasilev
Krasimir
K
D000327:Adsorption; D000595:Amino Acid Sequence; D000818:Animals; D032701:Biomimetics; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods; D006863:Hydrogen-Ion Concentration; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D011487:Protein Conformation; D016415:Sequence Alignment; D020349:Surface Plasmon Resonance / Q000295:instrumentation / Q000379:methods; D014783:Viscosity
D029721:Drosophila Proteins; D019476:Insect Proteins; C030951:resilin