4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + L-glutamine - Bacillus subtilis pyridoxal 5'-phosphate + L-glutamate + 3 H2O + phosphate - ? 415616 4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + L-glutamine - Geobacillus kaustophilus pyridoxal 5'-phosphate + L-glutamate + 3 H2O + phosphate - ? 415616 4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + L-glutamine the enzyme is involved in vitamin B6 biosynthesis Bacillus subtilis pyridoxal 5'-phosphate + L-glutamate + 3 H2O + phosphate - ? 415616 4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + L-glutamine L-glutamine binding triggers a cascade of conformational changes of Pdx2 (glutaminase subunit) that leads to a structure favorable for Pdx1 (pyridoxal 5'-phosphate synthase subunit) binding Bacillus subtilis pyridoxal 5'-phosphate + L-glutamate + 3 H2O + phosphate - ? 415616 4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + L-glutamine mechanistic studies. Pdx2 has glutaminase activity and channels ammonia to the active site of the PLP synthase subunit, Pdx1, where ribose-5-phosphate, glyceraldehyde-3-phosphate, and ammonia are condensed in a complex series of reactions. Under pre-steady-state conditions, a chromophoric intermediate is observed that accumulates upon addition of only two of the substrates, D-ribose 5-phosphate and glutamine. The intermediate is covalently bound to the protein. The phosphate unit of R5P is eliminated rather than hydrolyzed in route to intermediate formation Bacillus subtilis pyridoxal 5'-phosphate + L-glutamate + 3 H2O + phosphate - ? 415616 4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + L-glutamine preference of D-ribose 5-phosphate compared to D-ribulose 5-phosphate. Characterization of a novel chromophoric reaction intermediate. The chromophoric group of this intermediate is appended to the epsilon-amino group of Lys81 and that the new residue has the composition C5H6O2, corresponding to the elimination of one equivalent of inorganic phosphate, one molecule of water one additional proton from the original protonated imine adduct Bacillus subtilis pyridoxal 5'-phosphate + L-glutamate + 3 H2O + phosphate - ? 415616 4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + L-glutamine the ammonia generated at the YaaE active site is channelled to the active site of YaaD where pyridoxal 5'-phosphate formation occurs Bacillus subtilis pyridoxal 5'-phosphate + L-glutamate + 3 H2O + phosphate - ? 415616 4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + L-glutamine the synthase subunit of this enzyme, Pdx1, operates in concert with the glutaminase subunit, Pdx2, to catalyze the complex condensation of ribose 5-phosphate, glutamine and glyceraldehyde 3-phosphate to form pyridoxal 5'-phosphate. Many if not all of the reaction intermediates are covalently bound to the synthase subunit, thus making them difficult to isolate and characterize. By denaturing the enzyme at points along the reaction coordinate, the structures of three covalently bound intermediates are solved. Thes analysis reveals a 1,5 migration of the lysine amine linking the intermediate to the enzyme during the conversion of ribose 5-phosphate to pyridoxal 5'-phosphate Bacillus subtilis pyridoxal 5'-phosphate + L-glutamate + 3 H2O + phosphate - ? 415616 4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + L-glutamine two proteins form a complex that functions as a glutamine amidotransferase, with YaaE as the glutaminase domain and YaaD as the acceptor and pyridoxal 5'-phosphate synthesis domain. The synthase reaction can also utilize an external ammonium source but, in contrast to other glutamine amidotransferases, is dependent on YaaE under certain conditions Bacillus subtilis pyridoxal 5'-phosphate + L-glutamate + 3 H2O + phosphate - ? 415616 4.3.3.6 D-ribose 5-phosphate + D-glyceraldehyde 3-phosphate + NH3 - Geobacillus kaustophilus pyridoxal 5'-phosphate + 4 H2O + phosphate - ? 416840