Mannitol production in fungi during glucose catabolism.
The levels of phosphofructokinase (EC 2.7.1.11) and mannitol-1-phosphate dehydrogenase (EC 1.1.1.17) have been determined in a number of Mucor and Penicillium species. Mannitol-1-phosphate dehydrogenase was found in only one species of mucor, Mucor rouxii, and this with a specific activity much lower than that found in Penicillium species. All of the fungi tested in the Ascomycetes class exhibited mannitol-1-phosphate dehydrogenase activity. Interference from both mannitol-1-phosphate dehydrogenase and NADH oxidase (EC 1.6.99.5) caused some difficulty initially in detecting phosphofructokinase in Penicillium species; the Penicillium phosphofructokinase is very unstable. Penicillium notatum accumulates mannitol intracellularly; detection of mannitol-1-phosphate dehydrogenase and mannitol-1-phosphatase (EC 3.1.3.22) activity in cell-free extracts indicates that the mannitol is formed from glucose via fructose-6-phosphate and mannitol-1-phosphate; no direct reduction of fructose to mannitol could be detected. The mannitol-1-phosphate dehydrogenase was specific for mannitol-1-phosphate and fructose-6-phosphate; NADP+(H) could not replace NAD+(H). The phosphatase (EC3.1.3.22) exhibited a distinct preference for mannitol-1-phosphate as substrate; all other substrates tested exhibited less than 25% of the activity observed with mannitol-1-phosphate.
D000429:Alcohol Oxidoreductases / Q000378:metabolism; D001230:Aspergillus / Q000201:enzymology; D002474:Cell-Free System; D005658:Fungi / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D008353:Mannitol / Q000096:biosynthesis*; D009089:Mucor / Q000201:enzymology; D010407:Penicillium / Q000201:enzymology; D010732:Phosphofructokinase-1 / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D013045:Species Specificity; D013696:Temperature
D008353:Mannitol; D000429:Alcohol Oxidoreductases; D010732:Phosphofructokinase-1; D010744:Phosphoric Monoester Hydrolases; D005947:Glucose