Module IsoelectricPoint
source code
Calculate isoelectric points of polypeptides using methods of
Bjellqvist.
pK values and the methos are taken from:
* Bjellqvist, B.,Hughes, G.J., Pasquali, Ch., Paquet, N., Ravier, F.,
Sanchez, J.-Ch., Frutiger, S. & Hochstrasser, D.F. The focusing
positions of polypeptides in immobilized pH gradients can be predicted
from their amino acid sequences. Electrophoresis 1993, 14, 1023-1031.
* Bjellqvist, B., Basse, B., Olsen, E. and Celis, J.E. Reference
points for comparisons of two-dimensional maps of proteins from different
human cell types defined in a pH scale where isoelectric points correlate
with polypeptide compositions. Electrophoresis 1994, 15, 529-539.
I designed the algorithm according to a note by David L. Tabb,
available at:
http://fields.scripps.edu/DTASelect/20010710-pI-Algorithm.pdf
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positive_pKs = {'H': 5.98, 'K': 10.0, 'Nterm': 7.5, 'R': 12.0}
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negative_pKs = {'C': 9.0, 'Cterm': 3.55, 'D': 4.05, 'E': 4.45,...
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pKcterminal = {'D': 4.55, 'E': 4.75}
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pKnterminal = {'A': 7.59, 'E': 7.7, 'M': 7.0, 'P': 8.36, 'S': ...
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charged_aas = ('K', 'R', 'H', 'D', 'E', 'C', 'Y')
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negative_pKs
- Value:
{'C': 9.0, 'Cterm': 3.55, 'D': 4.05, 'E': 4.45, 'Y': 10.0}
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pKnterminal
- Value:
{'A': 7.59,
'E': 7.7,
'M': 7.0,
'P': 8.36,
'S': 6.93,
'T': 6.82,
'V': 7.44}
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