pard 0.1.4

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PARD (Physicochemical Amino acid Replacement Distances)

Overview

Amino acid replacements (also referred to as substitutions) are changes from one amino acid to a different one in a protein - and there are different ways to assess the difference between the two amino acids that come into play in an amino acid replacement.

One can look at one or several properties' discrepancy between two amino acids. To list only a few: polarity [1][3][4], molecular volume / relative sizes of amino-acid side chains [1][3][4], mean number of lone pair electrons on the side-chain [2], maximum moment of inertia for rotation at the α―β bond [2] or at the β―γ bond [2] or at the γ―δ bond [2], presence of a pyrrolidine ring (proline (P)) [2], experimental protein activity and stability after exchanging one amino acid into another [5], etc.

pard is a package designed to make those Physicochemical Amino acid Replacement Distances calculations straightforward with Python.

One typical use is to establish a 'distance' between a wild-type protein and its mutated version.

Getting started

Install from PyPI (recommended)

To use pard, run pip install pard in your terminal.

Usage

import pard

amino_acid_1: str = "W"  # Tryptophan
amino_acid_2: str = "L"  # Leucine
distance: int = pard.grantham.grantham(amino_acid_1, amino_acid_2)
print(distance)

will output:

>>> 61

which is the correct value [1].

Unit tests

Name                              Stmts   Miss  Cover   Missing
---------------------------------------------------------------
pard\__init__.py                      3      0   100%
pard\grantham.py                      3      0   100%
pard\raw_python_dictionaries.py      19     10    47%   2-403, 407-810, 814-1217, 1229-1632, 1643-2046
tests\__init__.py                     0      0   100%
tests\test_grantham.py               17      0   100%
tests\test_pard.py                    3      0   100%
---------------------------------------------------------------
TOTAL                                45     10    78%

About the source code

• Follows PEP8 Style Guidelines.
• All variables are correctly type-hinted, reviewed with static type checker mypy.

Useful links:

• Corresponding GitHub repository
• Corresponding PyPI page

References

• [1] Grantham, R., 1974. Amino acid difference formula to help explain protein evolution. science, 185(4154), pp.862-864.
• [2] Sneath, P.H.A., 1966. Relations between chemical structure and biological activity in peptides. Journal of theoretical biology, 12(2), pp.157-195.
• [3] Epstein, C.J., 1967. Non-randomness of ammo-acid changes in the evolution of homologous proteins. Nature, 215(5099), pp.355-359.
• [4] Miyata, T., Miyazawa, S. and Yasunaga, T., 1979. Two types of amino acid substitutions in protein evolution. Journal of molecular evolution, 12(3), pp.219-236.
• [5] Yampolsky, L.Y. and Stoltzfus, A., 2005. The exchangeability of amino acids in proteins. Genetics, 170(4), pp.1459-1472.