Abstract: THE enzyme pullulanase1 is a bacterial R-enzyme in that it is capable of cleaving certain α 1→6 glucosidic bonds where these occur together with α 1→4 glucosidic bonds as in pullulan, starch and dextrins. The substrate specificity of this enzyme has recently been reported2 to embrace oligosaccharides and dextrins containing as few as two 1→4 linked α-D-glucopyranoside units in the ‘A’ chain and two such units in the ‘B’ chain. Thus, a tetra-saccharide linked 2 on 2 is the smallest known substrate for the hydrolytic action of this enzyme2.