For a long time enzymes have been considered as highly specific catalysts obeying the rule"one enzyme,one activity".However,in recent years an increasing number of enzymes,which demonstrate non-conventional reactions,was reported.Numerous reports indicate that enzymes are catalytically more flexible than originally assumed and such an activity got the name"promiscuous".Among promiscuous enzymes especially hydrolases have appeared broad substrate specificities or side activities.During our studies we noticed that also Hintl enzyme has shown promiscuity.Hint-1(the histidine triad nucleotide binding protein 1) belongs to the first branch of the HIT superfamily,the enzymes acting as nucleotidylyl hydrolases and transferases.