Nomenclature and Representation of Biopolymer Sequences by Chemical Abstracts Service

Currently there are over 120,000 protein sequences and over 35,000 nucleic acid sequences in the Chemical Abstracts Service (CAS) machine and manual files. Approximately 20,000 new sequences are reported each year. Both the current number of existing sequences and the rapid increase in the number of new sequences being reported require maintaining and developing a nomenclature system to keep up with advances in the field. Clear, unambiguous and unique names are needed in order to keep track of and to report biopolymer sequence information in abstracts, databases, and in indexes. The CAS naming and representation of amino acids, peptides, and nucleic acids including those with both short and long sequences are presented. Problems encountered with altered sequences of natural products, and those with partial sequences or with undefined or ambiguous groups are discussed.