Some aspects of this disclosure relate to strategies, systems, methods, compositions, and kits that are useful for production (e.g., evolution) of cytidine deaminase protein variants that are characterized by increased soluble expression and/or stability relative to the wild-type cytidine deaminase protein from which they are evolved. In some embodiments, evolved cytidine deaminase variants described by the disclosure are useful for incorporation into targeted nucleic acid editing proteins, for example in fusion proteins with a Cas9 domain or variant thereof.