[32] Glutamine amidotransferases

摘要: Publisher Summary This chapter provides an overview of glutamine amidotransferases, which utilize the amide for biosynthesis several amino acids, purine and pyrimidine nucleotides, two coenzymes, glucosamine, antibiotics. Most amidotransferases exhibit common properties: (1) capacity to NH 3 in place glutamine, (2) selective inactivation glutamine-dependent activity by alkylation active site cysteine residue with affinity analogs, 6-diazo-5-oxonorleueine, or L-2-amino-4-oxo-5-chloropentanate, (3) glutaminase activity. These properties imply a functional domain transfer integrated one more domains covalent attachment N specialized catalytic features each enzyme. In case anthranilate synthase p -aminobenzoate synthase, acid sequence homology is detected domains. As consequence required activity, precautions are usually prevent oxidative inactivation. Thiol reagents often employed but amidophosphoribosyltransferase, deoxygenation buffers effective.