Regex Tester & Validator

Parses a single ProForma-style peptide modification used in mass spectrometry: an optional residue sequence (any chars except newline, colon, or #), an optional colon-delimited section (e.g., isotope or cross-link info), and an optional '#ModificationName' tag where the alphanumeric name may carry a mass override in parentheses, like #Oxidation(15.9949). Capture groups expose the sequence, colon section, modification name, and numeric mass value.