Calculating the charge of a peptide computationally I was wondering how I can calculate the charge of a protein peptide (e.g. "RKTTLVPNTQTASPR") computationally in R or another tool.
A quick google search turns up protcalc, which is able to give a nice pH-dependent table of peptide charges (yours ranges from 3.1 at pH 4 to 1.5 at pH 10). It's on sourceforge, so hopefully the source code (and maybe a publication) is somewhere in there. Granted, this isn't R, but it's not clear from your post how necessary that really is.

BTW, in general "best and most accurate" turns out to be highly subjective (at least the "best" part of that).