1. Academic Validation
  2. Expression and biochemical characterization of the human enzyme N-terminal asparagine amidohydrolase

Expression and biochemical characterization of the human enzyme N-terminal asparagine amidohydrolase

  • Biochemistry. 2011 Apr 12;50(14):3025-33. doi: 10.1021/bi101832w.
Jason R Cantor 1 Everett M Stone George Georgiou
Affiliations

Affiliation

  • 1 Department of Chemical Engineering, Institute for Cellular and Molecular Biology, Section of Molecular Genetics and Microbiology, University of Texas, Austin, Texas 78712, United States.
Abstract

The enzymatic deamidation of N-terminal L-Asn by N-terminal asparagine amidohydrolase (NTAN1) is a feature of the ubiquitin-dependent N-end rule pathway of protein degradation, which relates the in vivo half-life of a protein to the identity of its N-terminal residue. Herein, we report the Bacterial expression, purification, and biochemical characterization of human NTAN1 (hNTAN1). We show here that hNTAN1 is highly selective for the hydrolysis of N-terminal peptidyl L-Asn but fails to deamidate free L-Asn or L-Gln, N-terminal peptidyl L-Gln, or acetylated N-terminal peptidyl L-Asn. Similar to Other N-terminal deamidases, hNTAN1 is shown to possess a critical Cys residue that is absolutely required for catalysis, corroborated in part by abolishment of activity through the Cys75Ala point mutation. We also present evidence that the exposure of a conserved L-Pro at the N-terminus of hNTAN1 following removal of the initiating L-Met is important for the function of the Enzyme. The results presented here should assist in the elucidation of molecular mechanisms underlying the neurological defects of NTAN1-deficient mice observed in Other studies, and in the discovery of potential physiological substrates targeted by the Enzyme in the modulation of protein turnover via the N-end rule pathway.

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