3tkj
From Proteopedia
Crystal Structure of Human Asparaginase-like Protein 1 Thr168Ala
Structural highlights
Function[ASGL1_HUMAN] Has both L-asparaginase and beta-aspartyl peptidase activity. May be involved in the production of L-aspartate, which can act as an excitatory neurotransmitter in some brain regions. Is highly active with L-Asp beta-methyl ester. Besides, has catalytic activity toward beta-aspartyl dipeptides and their methyl esters, including beta-L-Asp-L-Phe, beta-L-Asp-L-Phe methyl ester (aspartame), beta-L-Asp-L-Ala, beta-L-Asp-L-Leu and beta-L-Asp-L-Lys. Does not have aspartylglucosaminidase activity and is inactive toward GlcNAc-L-Asn. Likewise, has no activity toward glutamine.[1] Publication Abstract from PubMedThe human asparaginase-like protein 1 (hASRGL1) catalyzes the hydrolysis of l-asparagine and isoaspartyl-dipeptides. As an N-terminal nucleophile (Ntn) hydrolase superfamily member, the active form of hASRGL1 is generated by an intramolecular cleavage step with Thr168 as the catalytic residue. However, in vitro, autoprocessing is incomplete ( approximately 50%), fettering the biophysical characterization of hASRGL1. We circumvented this obstacle by constructing a circularly permuted hASRGL1 that uncoupled the autoprocessing reaction, allowing us to kinetically and structurally characterize this enzyme and the precursor-like hASRGL1-Thr168Ala variant. Crystallographic and biochemical evidence suggest an activation mechanism where a torsional restraint on the Thr168 side chain helps drive the intramolecular processing reaction. Cleavage and formation of the active site releases the torsional restriction on Thr168, which is facilitated by a small conserved Gly-rich loop near the active site that allows the conformational changes necessary for activation. Uncoupling Intramolecular Processing and Substrate Hydrolysis in the N-Terminal Nucleophile Hydrolase hASRGL1 by Circular Permutation.,Li W, Cantor JR, Yogesha SD, Yang S, Chantranupong L, Liu JQ, Agnello G, Georgiou G, Stone EM, Zhang Y ACS Chem Biol. 2012 Aug 29. PMID:22891768[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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