Converts adenosylcobinamide (AdoCbi) to adenosylcobyric acid (AdoCby), an intermediate of the de novo coenzyme B12 biosynthetic route. adenosylcob(III)inamide + H2O = (R)-1-aminopropan-2-ol + adenosylcob(III)yrate Cofactor biosynthesis; dicyanocobinamide salvage pathway. Belongs to the CbiZ family.