. . . . "Catalyzes the removal of elemental sulfur and selenium atoms from cysteine and selenocysteine to produce alanine. Functions as a sulfur delivery protein for NAD, biotin and Fe-S cluster synthesis. Transfers sulfur on 'Cys-456' of ThiI in a transpersulfidation reaction. Functions also as a selenium delivery protein in the pathway for the biosynthesis of selenophosphate (By similarity)." .