So, I'm digesting a protein sequence with an enzyme (for your curiosity, Asp-N) which cleaves before the proteins coded by B or D in a single-letter coded sequence. My actual analysis uses String#scan for the captures. I'm trying to figure out why the following regular expression doesn't digest it correctly...
(\w*?)(?=[BD])|(.*\b)
where the antecedent (.*\b) exists to capture the end of the sequence.
For:
MTMDKPSQYDKIEAELQDICNDVLELLDSKGDYFRYLSEVASGDN
This should give something like: [MTM, DKPSQY, DKIEAELQ, DICN, DVLELL, DSKG, ... ] but instead misses each D in the sequence.
I've been using http://www.rubular.com for troubleshooting, which runs on 1.8.7 although I've also tested this REGEX on 1.9.2 to no avail. It is my understanding that zero-width lookahead assertions are supported in both versions of ruby. What am I doing wrong with my regex?