Comparative effects of cationic triarylmethane, phenoxazine and phenothiazine dyes on horse serum butyrylcholinesterase

Yucel Y. Y. , TACAL Ö., Ozer I.

ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS, vol.478, no.2, pp.201-205, 2008 (Peer-Reviewed Journal) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 478 Issue: 2
  • Publication Date: 2008
  • Doi Number: 10.1016/
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.201-205
  • Keywords: horse serum butyrylcholinesterase, triarylmethane dyes, phenoxazine dyes, phenothiazine dyes, cholinesterase inhibition, nile blue, HUMAN PLASMA CHOLINESTERASE, AMINO-ACID-RESIDUES, ACETYLCHOLINESTERASE, INHIBITION, DERIVATIVES, PROTEINS


The kinetic effects of a selection of triarylmethane, phenoxazine and phenothiazine dyes (pararosaniline (PR), malachite green (MG), methyl green (MeG); meldola blue (MB), nile blue (NB), nile red (NR); methylene blue (MethB)) and of ethopropazine on horse serum butyrylcholinesterase were studied spectrophotometrically at 25 degrees C in 50 mM MOPS buffer, pH 8, using butyrylthiocholine as substrate. PR, MeG, MB and ethopropazine acted as linear mixed type inhibitors of the enzyme, with respective K(i) values of 4.5 +/- 0.50 mu M, 0.41 +/- 0.007 mu M, 0.44 +/- 0.086 mu M and 0.050 +/- 0.0074 mu M. MG, NB, MethB and NR caused complex, nonlinear inhibition pointing to cooperative binding at two sites. Intrinsic K ' values ([I](2)(0.5) extrapolated to [S]=0) for MG, NB, NR and MethB were 0.20 +/- 0.096 mu M, 0.0018 +/- 0.0015 mu M, 0.92 +/- 0.23 mu M and 0.23 +/- 0.08 mu M. NB stood out as a potent inhibitor effective at nM levels. Comparison of inhibitory effects on horse and human serum butyrylcholinesterases suggested that the two enzymes must have distinct microstructural features. (c) 2008 Elsevier Inc. All rights reserved.