Fig. 1. Sequence alignments and secondary structure assignment. The AS sequences of selected AS family enzymes from low to high organisms are aligned: GluAT, Glu-tRNA^Gln amidotransferase, Bacillus subtilis (gi: 2589195); Yeast Amd2p, a putative amidase, Saccharomyces cerevisiae (gi: 6320448); Celeg, a putative amidase, Caenorhabditis elegans (gi: 6425411); VDHAP, vitamin D₃ hydroxylase-associated protein, Gallus domesticus (gi: 1079452); FAAH, fatty acid amide hydrolase, Homo sapiens (gi: 4557575). The secondary structure assignment is shown at the top of the sequence. The solid-line boxes indicate the three invariant residues of the catalytic triad and the dotted-line box indicates the highly conserved residue that provides the augmenting catalytic role (see text). Asterisks indicate the residues comprising the oxyanion hole.