massShift {Peptides}

Calculate the mass difference of modified peptides.

Description

This function calculates the mass difference of peptides introduced by chemical modifications or heavy isotope labelling.

Usage

massShift(seq, label = "none", aaShift = NULL, monoisotopic = TRUE)

Arguments

seq

An amino-acids sequence, in one letter code.

label

Set a predefined heavy isotope label. Accepts "none", "silac_13c", "silac_13c15n" and "15n". Overwrites input in aaShift.

aaShift

Define the mass difference in Dalton of given amino acids as a named vector. Use the amino acid one letter code as names and the mass shift in Dalton as values. N-terminal and C-terminal modifications can be defined by using "Nterm =" and "Cterm =", respectively.

monoisotopic

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

Source

For the predefined heavy isotope labels, compare:

• silac_13c Unimod 188

• silac_13c15n Unimod 259 and Unimod 267

• 15n Unimod 994, Unimod 995, Unimod 996 and Unimod 897

Examples

massShift("EGVNDNECEGFFSAR", label = "silac_13c")
massShift("EGVNDNECEGFFSAR", aaShift = c(K = 6.020129, R = 6.020129))