title: Cytosinine: pyridoxal phosphate tautomerase, a new enzyme in the blasticidin S biosynthetic pathway.
abstract: Cytosinine--the nucleoside portion of blasticidin S--and pyridoxal phosphate were incubated with cell-free extracts of Streptomyces griseochromogenes prepared in D2O. 2H NMR analysis of recovered cytosinine showed it to contain deuterium enrichments at H-4' and H-2'. No exchange was observed with either boiled extract or from cytosinine and pyridoxal phosphate alone. These results reveal the presence of a tautomerase activity that contributes to the net transamination at C-4' in the conversion of cytosylglucuronic acid to blasticidin S, and its discovery supports the role of cytosinine as a biosynthetic intermediate.
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis 97331-4003, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Gould
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000935:Antifungal Agents / Q000096:biosynthesis* / Q000302:isolation & purification; D003596:Cytosine / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000378:metabolism*; D005285:Fermentation; D009705:Nucleosides / Q000096:biosynthesis / Q000302:isolation & purification; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D013237:Stereoisomerism; D013302:Streptomyces
chemical_list: D000935:Antifungal Agents; D009705:Nucleosides; C095343:cytosinine; D011732:Pyridoxal Phosphate; C004500:blasticidin S; D003596:Cytosine