Deuterium-Enhanced Raman Spectroscopy for Histidine pKa Determination in a pH-Responsive Hydrogel
(2020) In Biophysical Journal 119(9). p.1701-1705- Abstract
We report here a method for the determination of the pKa of histidine in complex or heterogeneous systems amenable to neither solid-state nor solution NMR spectroscopy. Careful synthesis of a fluorenylmethyloxycarbonyl- and trityl-protected, C2-deuterated histidine produces a vibrational-probe-equipped amino acid that can readily be incorporated into any peptide accessible by standard solid-phase methods. The frequency of the unique, Raman-active stretching vibration of this C2-D probe is a clear reporter of the protonation state of histidine. We investigate here a pH-sensitive peptide that self-assembles to form a hydrogel at neutral pH. The pKa of the lone histidine residue in the peptide, which is likely... (More)
We report here a method for the determination of the pKa of histidine in complex or heterogeneous systems amenable to neither solid-state nor solution NMR spectroscopy. Careful synthesis of a fluorenylmethyloxycarbonyl- and trityl-protected, C2-deuterated histidine produces a vibrational-probe-equipped amino acid that can readily be incorporated into any peptide accessible by standard solid-phase methods. The frequency of the unique, Raman-active stretching vibration of this C2-D probe is a clear reporter of the protonation state of histidine. We investigate here a pH-sensitive peptide that self-assembles to form a hydrogel at neutral pH. The pKa of the lone histidine residue in the peptide, which is likely responsible for this pH-dependent behavior, cannot be investigated by NMR spectroscopy because of the supramolecular, soft nature of the gel. However, after synthesizing a C2-deuterated-histidine-containing peptide, we were able to follow the protonation state of histidine throughout a pH titration using Raman difference spectroscopy, thereby precisely determining the pKa of interest.
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- author
- Braun, Gabriel A. LU ; Pogostin, Brett H. ; Pucetaite, Milda LU ; Londergan, Casey H. and Åkerfeldt, Karin S. LU
- organization
- publishing date
- 2020
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Biophysical Journal
- volume
- 119
- issue
- 9
- pages
- 1701 - 1705
- publisher
- Cell Press
- external identifiers
-
- pmid:33080220
- scopus:85092788691
- ISSN
- 0006-3495
- DOI
- 10.1016/j.bpj.2020.09.011
- language
- English
- LU publication?
- yes
- id
- ede2ad87-ec15-4a5c-9ed1-022182242b8f
- date added to LUP
- 2020-10-26 09:23:42
- date last changed
- 2024-09-19 08:42:06
@article{ede2ad87-ec15-4a5c-9ed1-022182242b8f, abstract = {{<p>We report here a method for the determination of the pK<sub>a</sub> of histidine in complex or heterogeneous systems amenable to neither solid-state nor solution NMR spectroscopy. Careful synthesis of a fluorenylmethyloxycarbonyl- and trityl-protected, C2-deuterated histidine produces a vibrational-probe-equipped amino acid that can readily be incorporated into any peptide accessible by standard solid-phase methods. The frequency of the unique, Raman-active stretching vibration of this C2-D probe is a clear reporter of the protonation state of histidine. We investigate here a pH-sensitive peptide that self-assembles to form a hydrogel at neutral pH. The pK<sub>a</sub> of the lone histidine residue in the peptide, which is likely responsible for this pH-dependent behavior, cannot be investigated by NMR spectroscopy because of the supramolecular, soft nature of the gel. However, after synthesizing a C2-deuterated-histidine-containing peptide, we were able to follow the protonation state of histidine throughout a pH titration using Raman difference spectroscopy, thereby precisely determining the pK<sub>a</sub> of interest.</p>}}, author = {{Braun, Gabriel A. and Pogostin, Brett H. and Pucetaite, Milda and Londergan, Casey H. and Åkerfeldt, Karin S.}}, issn = {{0006-3495}}, language = {{eng}}, number = {{9}}, pages = {{1701--1705}}, publisher = {{Cell Press}}, series = {{Biophysical Journal}}, title = {{Deuterium-Enhanced Raman Spectroscopy for Histidine pK<sub>a</sub> Determination in a pH-Responsive Hydrogel}}, url = {{http://dx.doi.org/10.1016/j.bpj.2020.09.011}}, doi = {{10.1016/j.bpj.2020.09.011}}, volume = {{119}}, year = {{2020}}, }