In vitro inhibition of choline acetyltransferase by a series of 2-benzylidene-3-quinuclidinones

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5565780

Capacio, B R

Ten substituted 2-benzylidene-3-quinuclidinones were synthesized and evaluated for their relative potency as in vitro inhibitors of choline acetyltransferase (ChAT). Acetylcholine (ACh) synthesis was followed radiometrically by the incorporation of labeled acetate originating from {sup 14}C-acetyl-CoA. Woolf-Augustinsson-Hofstee data analysis was used to calculate Vmax, Km, and Ki values. The inhibition was found to be noncompetitive or uncompetitive with respect to choline. Quantitative structure activity relationship correlations demonstrated a primary dependence on {kappa}-{sigma}, as well as steric properties of the substituted benzene ring. Additional radiometric and spectrophotometric were performed with 2-(3{prime}-methyl)-benzylidene-3-quinuclidinone, one of the more potent analogs, to further elucidate the inhibitory mechanism. ChAT-mediated cleavage of ACh was measured spectrophotometrically by following the appearance of NADH at 340 nanometers in an enzyme coupled assay. Lineweaver-Burk analysis indicated mixed or uncompetitive inhibition with respect to both substrates of the forward reaction, suggesting interference with a rate limiting step.

• Research Organization: Temple Univ., Philadelphia, PA (USA)
• OSTI ID: 5565780
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACETATES
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CARBOXYLIC ACID SALTS
CHOLINE
DATA ANALYSIS
DRUGS
ENZYME ACTIVITY
ENZYME INHIBITORS
ENZYMES
HYDROXY COMPOUNDS
IN VIVO
INHIBITION
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIPOTROPIC FACTORS
ORGANIC COMPOUNDS
QUATERNARY COMPOUNDS
REACTION KINETICS
SPECTROPHOTOMETRY
STRUCTURE-ACTIVITY RELATIONSHIPS
TRACER TECHNIQUES
TRANSFERASES