Amino acid residues involved in stereoselective inhibition of cholinesterases with bambuterol

作者：Bosak Anita; Gazic Ivana; Vinkovic Vladimir; Kovarik Zrinka^*

来源：Archives of Biochemistry and Biophysics, 2008, 471(1): 72-76.

DOI：10.1016/j.abb.2007.12.007

• carbamates
• acetylcholinesterase
• butyrylcholinesterase
• catalytic constants
• mutants
• carbamoylation

Bambuterol is a chiral carbamate known as selective inhibitor of butyrylcholinesterase (BChE). In order to relate bambuterol selectivity and stereoselectivity of cholinesterases to the active site residues, we studied the inhibition of recombinant mouse BChE, acetylcholinesterase (AChE) and six AChE mutants, employed to mimic BChE active site residues, by bambuterol enantiomers. Both enantiomers selectively inhibited BChE about 8000 times faster than AChE. The largest inhibition rate increase in comparison to AChE w.t. was observed with the F295L/Y337A mutant, showing that leucine 295 and alanine 337 are crucial residues in BChE for high bambuterol selectivity. All studied enzymes preferred inhibition by the R- over the S-bambuterol. The enlargement of the AChE choline binding site and of the acyl pocket by single or double mutations (Y337A, F295L/Y337A and F2971/Y337A) increased, in comparison to w.t. enzymes, inhibition rate constants of R- bambuterol more than that of S- bambuterol resulting in four times higher stereo selectivity. Peripheral site mutations (Y124Q and Y72N/Y124Q/Y337A) increased inhibition rate by S- more than R-bambuterol and consequently diminished the stereoselectivity.

• 出版日期2008-3-1
• 单位河北医科大学