Peptides (version 1.2.1)

mw: Compute the molecular weight of a protein sequence

Description

This function calculates the molecular weight of a protein sequence. It is calculated as the sum of the mass of each amino acid using the scale available on Compute pI/Mw tool.

Usage

mw(seq, monoisotopic = FALSE)

Arguments

seq

An amino-acids sequence

monoisotopic

A logical value 'TRUE' or 'FALSE' indicating if monoisotopic weights of amino-acids should be used

Details

The molecular weight is the sum of the masses of each atom constituting a molecule. The molecular weight is directly related to the length of the amino acid sequence and is expressed in units called daltons (Da). In Peptides the function mw computes the molecular weight using the same formulas and weights as ExPASy's "compute pI/mw" tool (Gasteiger et al., 2005).

References

Gasteiger, E., Hoogland, C., Gattiker, A., Wilkins, M. R., Appel, R. D., & Bairoch, A. (2005). Protein identification and analysis tools on the ExPASy server. In The proteomics protocols handbook (pp. 571-607). Humana Press. Chicago

Examples

# COMPARED TO ExPASy Compute pI/Mw tool
# http://web.expasy.org/compute_pi/
# SEQUENCE: QWGRRCCGWGPGRRYCVRWC 
# Theoretical pI/Mw: 9.88 / 2485.91 

mw("QWGRRCCGWGPGRRYCVRWC")
# [1] 2485.911