| http://www.w3.org/ns/prov#value | - Xaa1 is a naturally or nonnaturally occurring amino acid comprising an imidazole or thiazole ring, such as histidine or thiazolylalanine; wherein any of the carbon atoms of said amino acid are optionally substituted with hydrogen or with one or more alkyl groups, or with one or more halo groups; wherein the free amino group of said amino acid may be replaced with a hydroxyl or an alkoxy group, or
|