Figure 4From: A survey of orphan enzyme activitiesPublication year of original publications describing orphan activities. The publication date associated with the original source articles of all instances of orphans surveyed here is plotted (286 instances of orphans, corresponding to 228 activities), based upon the IUBMB record. In a number of cases more than one instance of an orphan activity was evaluated because the activity was reported in more than one species.Back to article page