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pH-Dependent Behavior of Surface-immobilized Artificial Leucine Zipper Proteins

Stevens, Molly M. and Allen, Stephanie and Sakata, Jill K. and Davies, Martyn C. and Roberts, Clive J. and Tendler, Saul J. B. and Tirrell, David A. and Williams, Philip M. (2004) pH-Dependent Behavior of Surface-immobilized Artificial Leucine Zipper Proteins. Langmuir, 20 (18). pp. 7747-7752. ISSN 0743-7463.

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The coiled-coil protein motif occurs in over 200 proteins and has generated interest for a range of applications requiring surface immobilization of the constituent peptides. This paper describes an investigation of the environment-responsive behavior of a monolayer of surface-immobilized artificial proteins, which are known to assemble to form coiled-coil structures in bulk solution. An extended version of the quartz crystal microbalance (QCM-D) and surface plasmon resonance (SPR) are independently employed to characterize the adsorption of the proteins to a gold surface. The data suggest that the molecules arrange in a closely packed layer orientated perpendicular to the surface. QCM-D measurements are also employed to measure pH-induced changes in the resonant frequency (f) and the energy dissipation factor (D) of a gold-coated quartz crystal functionalized with the formed monolayer. Exposure of the protein monolayer to a pH 4.5 solution results in a shift of 43 Hz in f and a shift of −0.7 × 10^(-6) in D as compared to pH 7.4. In contrast, increasing the pH to 11.2, results in f and D shifts of −17 Hz and 0.6 × 10^(-6), respectively. The magnitude of the observed shifts suggests that the proteins form a rigid layer at low pH that can be hydrated to a fluid layer as the pH is increased. These observations correlate with spectroscopic changes that indicate a reduction in the helical content of the protein in bulk solutions of high pH.

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Tirrell, David A.0000-0003-3175-4596
Additional Information:Copyright © 2004 American Chemical Society. Published In Issue August 31, 2004. Publication Date (Web): August 6, 2004. Received December 29, 2003. Revised June 10, 2004. Acknowledgment. The authors would like to thank Scientific and Medical Products Ltd (Cheshire, United Kingdom) for the kind loan of the Q-sense D300 measurements system and John Booth of Scientific and Medical Products for his comments and advice in carrying out these experiments. The authors would also like to thank Pharmacia Biosensor AB (Uppsala, Sweden) for the kind loan of the BIAcore 3000 biosensor instrument and Phil Buckle of Pharmacia Biosensor AB for his comments and advice in carrying out the experiments. The authors thank Dr. Chun Wang for help and advice with the CD measurements. Work at Nottingham was supported by the BBSRC and S.A. thanks Pfizer Global Research and Development (Sandwich, Kent, United Kingdom) for the funding of her lectureship.Workat Caltech was supported by the NSF Center for the Science and Engineering of Materials.
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Biotechnology and Biological Sciences Research Council (BBSRC)UNSPECIFIED
Pfizer Global Research and DevelopmentUNSPECIFIED
Issue or Number:18
Record Number:CaltechAUTHORS:20150120-162146672
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Official Citation:pH-Dependent Behavior of Surface-immobilized Artificial Leucine Zipper Proteins Molly M. Stevens, Stephanie Allen, Jill K. Sakata, Martyn C. Davies, Clive J. Roberts, Saul J. B. Tendler, David A. Tirrell, and Philip M. Williams Langmuir 2004 20 (18), 7747-7752
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53904
Deposited By: Katherine Johnson
Deposited On:21 Jan 2015 00:29
Last Modified:03 Oct 2019 07:53

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