Pfizer Handbook of Microbial Metabolites 



528 



from yeast^° and a penicillium mold^^ as well as from 

 higher animals, and it probably occurs in plants. Guano- 



OH 



O O H2N 



T T 

 I— O— P— O— P— O— CH2 ^o. 



OH OH 



OH OH 





OH OH 



Guanosine Diphosphate Mannose 



sine diphosphate fucose has been isolated from Aerobacter 

 aerogenes,^'- and this organism has an enzyme which con- 

 verts GDP-mannose to GDP-fucose. This conversion re- 

 quires TPNH and must involve several steps to accom- 

 plish the requisite epimerizations and reduction of the 

 terminal carbon atom. The functions of these guanosine 

 derivatives are unknown, but yeast elaborates a mannan, 

 and fucose is a proven constituent of bacterial polysac- 

 charides (as well as blood group specific polysaccharides 

 in higher animals). This may then be a form in which 

 sugars are modified and transported for incorporation 

 into polysaccharides. 



A substance of the vitamin B12 group isolated from 

 Nocardia rugosa has been identified as guanosine diphos- 

 phate factor B, i.e. a guanosine-5'-pyrophosphoric ester of 

 factor B in which ribose is linked to N-9 of guanine (par- 

 tial structure shown ).^^ 



10 E. Cabib and Luis F. Leloir, ibid. 206 779 (1954). 



^^ A. Ballio, C. Casinovi and G. Serlupi-Crescenzi, Biochim. et 

 Biophys. Acta 20 414 (1956). 



12 V. Ginsburg and H. N. Klrkman, J. Am. Chem. Soc. 80 3481, 

 4426 (1958). 



'^^ R. Barchielli, G. Boretti, A. DlMarco, P. Julita, A. Migliacci, 

 A. Minghetti and C. Spalla, Biochem. J. 74 382 (1960). 



