Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1994 Jun 1;47(11):2087-95.
doi: 10.1016/0006-2952(94)90085-x.

Inhibition of phenol sulfotransferase by pyridoxal phosphate

Affiliations

Inhibition of phenol sulfotransferase by pyridoxal phosphate

R Bartzatt et al. Biochem Pharmacol. .

Abstract

The biologically abundant cofactor, pyridoxal-5-phosphate (PLP), is a potent inhibitor of bovine phenol (aryl) sulfotransferase (PST). Preincubation of purified enzyme with as little as 1 microM PLP decreased PST activity by 50%. Excess 2-naphthol protected PST from inactivation by PLP, whereas 2-naphthyl sulfate and PAPS were not protective. Although PLP inhibition was apparently competitive with 2-naphthol, a steady-state kinetic Ki value could not be measured due to non-linear Lineweaver-Burk plots in the presence of the inhibitor. Kinetic progress curves revealed that this was due to progressive loss of activity during catalysis. The kinetics of inactivation of PST by PLP were pseudo-first-order and exhibited saturation. The derived KI value for the binding of PLP to PST in the initial reversible step was 23 microM, with a maximal rate of inactivation of 0.077 min(-1). Absorbance spectra of the PST/PLP complex indicated the formation of a Schiff base conjugate, and this is consistent with decreased electrophoretic mobility of the protein-PLP adduct in the presence of dodecyl sulfate only after reduction with borohydride. These results point to the possible regulation of an important detoxification enzyme by a ubiquitous cofactor.

PubMed Disclaimer

Publication types

LinkOut - more resources