Cantor JR, Stone EM, Chantranupong L, Georgiou G
The Human Asparaginase-Like Protein 1 hASRGL1is an Ntn Hydrolase with beta-aspartyl Peptidase Activity. [JOURNAL ARTICLE]
Biochemistry 2009 Oct 19.
Herein we report the bacterial expression, purification, and enzymatic characterization of the human asparaginase-like protein 1 (hASRGL1). We present evidence that hASRGL1 exhibits beta-aspartyl peptidase activity consistent with enzymes designated as plant-type asparaginases, which had thus far only been found in plants and bacteria. Similar to non-mammalian plant-type asparaginases, hASRGL1 is shown to be an Ntn hydrolase for which Thr168 serves as the essential N-terminal nucleophile for intramolecular processing and catalysis, corroborated in part by abolishment of both activities through the point-mutation Thr168Ala. In light of the activity profile reported here, ASRGL1s may act synergistically with protein L-isoaspartyl methyl transferase to relieve accumulation of potentially toxic isoaspartyl peptides in mammalian brain and other tissues.
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