Enzyme activity involved in glucose phosphorylation in two arbuscular mycorrhizal fungi: indication that polyP is not the main phosphagen

Enzyme activity involved in glucose phosphorylation, the first step of glyc olysis and the pentose phosphate pathway (PPP), in the spores, extra- and i ntraradical hyphae of Glomus etunicatum and G. coronatum was measured to cl arify the role of polyphosphate as a phosphagen. Hexokinase, which utilizes ATP as a phosphagen was active in the all components of both fungi, sugges ting that glucose can be metabolized generally through glycolysis/PPP. Poly phosphateglucakinase-type activity, in which polyphosphate is utilized as a phosphagen, was detectable in the spores and intraradical hyphae of both f ungi but negligible compared with that of hexokinase. Hexokinase and polyph osphateglucokinase-type activities were characterized and it seems likely t hat the apparent polyphosphateglucokinase activity can be attributed to bro ad substrate specificity of the hexokinase. (C) 2001 Elsevier Science Ltd. All rights reserved.