WURCS

WURCS is a machine-readable linear notation used to encode glycan (carbohydrate) structures. It provides a canonical string representation designed to preserve detailed structural information needed for glycomics research, including monosaccharide identities, stereochemistry, ring types, substituents, and glycosidic linkages, as well as branching patterns. The format is intended to support unambiguous storage, searching, and comparison of complex glycans in databases and computational workflows.

Conceptually, WURCS represents a glycan as a graph where nodes correspond to monosaccharide residues and edges to glycosidic linkages. This graph is translated into a text string with a defined syntax and separators that encode residue identity, linkage positions, anomericity, ring size, and other features. The encoding is designed to accommodate common variations such as different anomeric configurations, ring forms, and chemical modifications, while allowing placeholders for uncertain or unknown information.

WURCS plays a central role in glycoinformatics ecosystems. It is used by GlyTouCan, a major glycan registry, as a canonical representation for indexing and retrieval. Software libraries exist to parse and generate WURCS strings, and mappings to other glycan representations (such as GlycoCT) support interoperability across databases and tools.

Advantages of WURCS include its capacity to encode branched and highly diverse glycans in a standardized, query-friendly form and its usefulness for large-scale comparisons. Limitations include the complexity of the notation and the need for specialized tooling to parse and interpret the strings, as well as ongoing efforts to maintain interoperability with alternative representations.