Boric acid inhibits adenosine diphosphate-ribosyl cyclase non-competitively.
Adenosine diphosphate-ribosyl cyclase (ADP-ribosyl cyclase) is a ubiquitous enzyme in eukaryotes that converts NAD+ to cyclic-ADP-ribose (cADPR) and nicotinamide. A quantitative assay for cADPR was developed using capillary electrophoresis to separate NAD+, cADPR, ADP-ribose, and ADP with UV detection (254 nm). Using this assay, the apparent Km and Vmax for Aplysia ADP-ribosyl cyclase were determined to be 1.24+/-0.05 mM and 131.8+/-2.0 microM/min, respectively. Boric acid inhibited ADP-ribosyl cyclase non-competitively with a Ki of 40.5+/-0.5 mM. Boric acid binding to cADPR, determined by electrospray ionization mass spectrometry, was characterized by an apparent binding constant, KA, of 655+/-99 L/mol at pH 10.3.
Department of Environmental Health Sciences, Box 951772, University of California, 650 Charles E Young Dr South, Los Angeles, CA 90095-1772, USA.
Danny H
DH
Kim
Shane Que
SQ
Hee
Andrew J
AJ
Norris
Kym F
KF
Faull
Curtis D
CD
Eckhert
D036541:ADP-ribosyl Cyclase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D000818:Animals; D001048:Aplysia / Q000201:enzymology; D001888:Boric Acids / Q000494:pharmacology*; D019075:Electrophoresis, Capillary; D007700:Kinetics; D021241:Spectrometry, Mass, Electrospray Ionization
D001888:Boric Acids; D036541:ADP-ribosyl Cyclase; C032688:boric acid