title: Harmaline interactions with yeast invertase.
abstract: The effect of harmaline, a plant alkaloid has been studied on yeast invertase activity in the absence and presence of 50mM Na+ as a function of pH. Harmaline (1-3 mM) inhibited the invertase activity at pH 5.2, 6.8 and 8 both in the absence (44-92%) and (22-85%) of Na+ ions. Kinetic analysis revealed that harmaline is a non-competitive inhibitor of invertase, at pH 5.2 and 6.8 but at pH 8, it produced a mixed type of inhibition, Km increased by 450% and 175% and Vmax decreased by 82% and 63% in the absence and presence of 50mM Na ions respectively. The observed inhibition of invertase by harmaline was reversible in nature. These findings suggest that the presence of Na+ site is not a prerequisite for the inhibition of enzyme by harmaline.
authors.affiliation: Department of Biochemistry, Panjab University, Chandigarh.
authors.forename: R K
authors.initials: RK
authors.lastname: Gill
authors.forename: J
authors.initials: J
authors.lastname: Kaur
authors.forename: S
authors.initials: S
authors.lastname: Mahmood
authors.forename: J P
authors.initials: JP
authors.lastname: Nagpaul
authors.forename: A
authors.initials: A
authors.lastname: Mahmood
mesh_terms: D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000378:metabolism*; D006246:Harmaline / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D043324:beta-Fructofuranosidase
chemical_list: D006246:Harmaline; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase