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pKa Determination of a Histidine Residue in a Short Peptide Using Raman Spectroscopy

Pogostin, Brett H.; Malmendal, Anders LU ; Londergan, Casey H. and Åkerfeldt, Karin S. LU (2019) In Molecules (Basel, Switzerland) 24(3).
Abstract

Determining the pKa of key functional groups is critical to understanding the pH-dependent behavior of biological proteins and peptide-based biomaterials. Traditionally, ¹H NMR spectroscopy has been used to determine the pKa of amino acids; however, for larger molecules and aggregating systems, this method can be practically impossible. Previous studies concluded that the C-D stretches in Raman are a useful alternative for determining the pKa of histidine residues. In this study, we report on the Raman application of the C2-D probe on histidine's imidazole side chain to determining the pKa of histidine in a short peptide sequence. The pKa of the tripeptide was found via difference Raman spectroscopy to be 6.82, and this value was... (More)

Determining the pKa of key functional groups is critical to understanding the pH-dependent behavior of biological proteins and peptide-based biomaterials. Traditionally, ¹H NMR spectroscopy has been used to determine the pKa of amino acids; however, for larger molecules and aggregating systems, this method can be practically impossible. Previous studies concluded that the C-D stretches in Raman are a useful alternative for determining the pKa of histidine residues. In this study, we report on the Raman application of the C2-D probe on histidine's imidazole side chain to determining the pKa of histidine in a short peptide sequence. The pKa of the tripeptide was found via difference Raman spectroscopy to be 6.82, and this value was independently confirmed via ¹H NMR spectroscopy on the same peptide. The C2-D probe was also compared to other Raman reporters of the protonation state of histidine and was determined to be more sensitive and reliable than other protonation-dependent signals. The C2-D Raman probe expands the tool box available to chemists interested in directly interrogating the pKa's of histidine-containing peptide and protein systems.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
1H NMR spectroscopy, acid dissociation constant, deuterium replacement, histidine, isotopic labeling, peptides, proteins, Raman spectroscopy, vibrational probes
in
Molecules (Basel, Switzerland)
volume
24
issue
3
publisher
Molecular Diversity Preservation International
external identifiers
  • scopus:85060533272
ISSN
1420-3049
DOI
10.3390/molecules24030405
language
English
LU publication?
yes
id
4542278b-fdc3-4716-80bf-8ceca9fd72d4
date added to LUP
2019-02-05 12:47:53
date last changed
2019-05-08 03:00:26
@article{4542278b-fdc3-4716-80bf-8ceca9fd72d4,
  abstract     = {<p>Determining the pKa of key functional groups is critical to understanding the pH-dependent behavior of biological proteins and peptide-based biomaterials. Traditionally, ¹H NMR spectroscopy has been used to determine the pKa of amino acids; however, for larger molecules and aggregating systems, this method can be practically impossible. Previous studies concluded that the C-D stretches in Raman are a useful alternative for determining the pKa of histidine residues. In this study, we report on the Raman application of the C2-D probe on histidine's imidazole side chain to determining the pKa of histidine in a short peptide sequence. The pKa of the tripeptide was found via difference Raman spectroscopy to be 6.82, and this value was independently confirmed via ¹H NMR spectroscopy on the same peptide. The C2-D probe was also compared to other Raman reporters of the protonation state of histidine and was determined to be more sensitive and reliable than other protonation-dependent signals. The C2-D Raman probe expands the tool box available to chemists interested in directly interrogating the pKa's of histidine-containing peptide and protein systems.</p>},
  articleno    = {405},
  author       = {Pogostin, Brett H. and Malmendal, Anders and Londergan, Casey H. and Åkerfeldt, Karin S.},
  issn         = {1420-3049},
  keyword      = {1H NMR spectroscopy,acid dissociation constant,deuterium replacement,histidine,isotopic labeling,peptides,proteins,Raman spectroscopy,vibrational probes},
  language     = {eng},
  month        = {01},
  number       = {3},
  publisher    = {Molecular Diversity Preservation International},
  series       = {Molecules (Basel, Switzerland)},
  title        = {pKa Determination of a Histidine Residue in a Short Peptide Using Raman Spectroscopy},
  url          = {http://dx.doi.org/10.3390/molecules24030405},
  volume       = {24},
  year         = {2019},
}