Biochemistry of filamentous fungi. II. The quantitative significance of an oxidative pathway during the growth of Penicillum chrysogenum.

The direct oxidation of glucose via glucose-6phosphate, 6-phosphogluconate, ribulose-5-phosphate, ribose-5-phosphate, etc., referred to as the hexosemonophosphate (HMP) or "oxidative pathway"3 may be an important mechanism of glucose metabolism in various tissues (Dickens, 1952; Horecker, 1953; and Weinhouse, 1954). In fact, Horecker recently postulated that the oxidative pathway, involving the phosphate esters mentioned above and others, may be cyclic in nature and an independent means for the complete oxidation of glucose. In addition to functioning as an oxidative mechanism, the HMP pathway also furnishes such cellular building blocks as ribose (Cohen, 1951), and perhaps others. This paper presents results of experiments which indicate that a mechanism which preferentially liberates the first carbon atom of glucose plays a major role in the metabolism of glucose during the growth of Penicillium chrysogenum. (Heath et al., 1953; Heath and Koffler, 1953, 1955). The first indication of this was obtained by Blumenthal (1952), who noted that a greater percentage of the radioactivity appeared in the C02 from glucose-i-C'4 than from uniformlylabeled glucose (glucose-U-C04) when resting celLs of this organism were allowed to metabolize these substrates. The data of de Fiebre and