SIMILARITY BETWEEN PYRIDOXAL PYRIDOXAMINE PHOSPHATE-DEPENDENT ENZYMESINVOLVED IN DIDEOXY AND DEOXYAMINOSUGAR BIOSYNTHESIS AND OTHER PYRIDOXAL-PHOSPHATE ENZYMES

A multiple sequence alignment among aspartate aminotransferase, dialky lglycine decarboxylase, and serine hydroxymethyltransferase (DAS) was used for profile databank search. The DAS profile could detect similar ities to other pyridoxal or pyridoxamine phosphate-dependent enzymes, like several gene products involved in dideoxysugar and deoxyaminosuga r synthesis. The alignment among DAS and such gene products shows the conservation of aspartate 222 and lysine 258, which, in aspartate amin otransferase, interacts with the N1 of the coenzyme pyridine ring and forms the internal Schiff base, respectively. The lysine is replaced b y histidine in the pyridoxamine phosphate-dependent gene products. The alignment indicates also that the region encompassing the coenzyme bi nding site is the most conserved.