In process biotechnology, purification of proteins from complex biological mixtures involves a series of complicated recovery steps, each of which can compromise the purity and yield of the desired product. An advance in this area has been the introduction of self-cleaving protein linkers, achieved by combining binding domains with modified self-splicing protein elements known as inteins. However, this system has drawbacks: it can require use of additional compounds; it can be accompanied by unwanted cleavage, requiring an additional purification step; and it can diminish solubility and purification efficiency. This technolgy is for a non-naturally occuring self-cleaving intien with improved control of the cleavage activity.