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Type: Journal article
Title: Observing the temperature dependent transition of the GP2 peptide using terahertz spectroscopy
Author: Sun, Y.
Zhu, Z.
Chen, S.
Balakrishnan, J.
Abbott, D.
Ahuja, A.
Pickwell-MacPherson, E.
Citation: PLoS One, 2012; 7(11):1-8
Publisher: Public Library of Science
Issue Date: 2012
ISSN: 1932-6203
Statement of
Yiwen Sun, Zexuan Zhu, Siping Chen, Jega Balakrishnan, Derek Abbott, Anil T. Ahuja and Emma Pickwell-MacPherson
Abstract: The GP2 peptide is derived from the Human Epidermal growth factor Receptor 2 (HER2/nue), a marker protein for breast cancer present in saliva. In this paper we study the temperature dependent behavior of hydrated GP2 at terahertz frequencies and find that the peptide undergoes a dynamic transition between 200 and 220 K. By fitting suitable molecular models to the frequency response we determine the molecular processes involved above and below the transition temperature (TD). In particular, we show that below TD the dynamic transition is dominated by a simple harmonic vibration with a slow and temperature dependent relaxation time constant and that above TD, the dynamic behavior is governed by two oscillators, one of which has a fast and temperature independent relaxation time constant and the other of which is a heavily damped oscillator with a slow and temperature dependent time constant. Furthermore a red shifting of the characteristic frequency of the damped oscillator was observed, confirming the presence of a non-harmonic vibration potential. Our measurements and modeling of GP2 highlight the unique capabilities of THz spectroscopy for protein characterization.
Keywords: Humans; Saliva; Breast Neoplasms; Peptides; Receptor, erbB-2; Models, Statistical; Tumor Markers, Biological; Refractometry; Oscillometry; Temperature; Absorption; Terahertz Spectroscopy; Molecular Weight; Fourier Analysis; Physics; Time Factors; Spectrophotometry; Female
Rights: © 2012 Sun et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricteduse, distribution, and reproduction in any medium, provided the original author and source are credited.
RMID: 0020123347
DOI: 10.1371/journal.pone.0050306
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Appears in Collections:Electrical and Electronic Engineering publications

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