This package cleaves polypeptide sequences. The cleavage rules are taken from: https://web.expasy.org/peptide_cutter/peptidecutter_enzymes.html
cleaver is part of Bioconductor.
install.packages("devtools")
library("devtools")
install_github("sgibb/cleaver")
## load library
library("cleaver")
## Gastric juice peptide 1 (UniProtKB/Swiss-Prot: GAJU_HUMAN/P01358)
gaju <- "LAAGKVEDSD"
cleave(gaju, "trypsin")
# $LAAGKVEDSD
# [1] "LAAGK" "VEDSD"
cleave(gaju, "trypsin", missedCleavages=1)
# $LAAGKVEDSD
# [1] "LAAGKVEDSD"
cleave(gaju, "trypsin", missedCleavages=0:1)
# $LAAGKVEDSD
# [1] "LAAGK" "VEDSD" "LAAGKVEDSD"
cleave(gaju, "pepsin")
# $LAAGKVEDSD
# [1] "LAAGKVEDSD"
# (no cleavage)