Fungal glucose 6-phosphate dehydrogenase and E.coli alkaline phosphatase were denatured either by physical or by chemical means. Invitro reconstitution of these denatured enzymes was assisted by 70S E.coli ribosome, as shown by the recovery of their catalytic competence. Almost total recovery of the activities of completely inactivated enzymes was obtained when 70S ribosome was present at about equimolar concentration with the enzyme molecules at 37C and 50C, respectively.