#!/usr/bin/env perl
use warnings;

@proteins=qw(DAAAAATTLTTTAMTTTTTTCKMMFRPPPPPGGGGGGGGGGGG ALTAMCMNVWEITYHKGSDVNRRASFAQPPPQPPPPLLAIKPASDASD);

for $protein (@proteins) {
	if ($protein =~ m/(KR)!P/g) {                       
				$protein =~ s/(KR)/$1=/;
				@new_peptides = split ('=',$protein);
	}
}

for (@new_peptides) {
	print "The peptide is $new_peptides\n";
}