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Updated: Oct 19, 2025

Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase
Published on: November 23, 2016
Active site characterization and activity of the human aspartyl (asparaginyl) β-hydroxylase
Jenna M Greve1, Andrew M Pinkham1, Zechariah Thompson1
1Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA.
Abstract:
Human aspartyl/asparaginyl beta-hydroxylase (HAAH) is a member of the superfamily of nonheme Fe2+/α-ketoglutarate (αKG) dependent oxygenase enzymes with a noncanonical active site. HAAH hydroxylates epidermal growth factor (EGF) like domains to form the β-hydroxylated product from substrate asparagine or aspartic acid and has been suggested to have a negative impact in a variety of cancers. In addition to iron, HAAH also binds divalent calcium, although the role of the latter is not understood. Herein, the metal binding chemistry and influence on enzyme stability and activity have been evaluated by a combined biochemical and biophysical approach. Metal binding parameters for the HAAH active site were determined by use of isothermal titration calorimetry, demonstrating a high-affinity regulatory binding site for Ca2+ in the catalytic domain in addition to the catalytic Fe2+ cofactor. We have analyzed various active site derivatives, utilizing LC-MS and a new HPLC technique to determine the role of metal binding and the second coordination sphere in enzyme activity, discovering a previously unreported residue as vital for HAAH turnover. This analysis of the in vitro biochemical function of HAAH furthers the understanding of its importance to cellular biochemistry and metabolic pathways.
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