title: Comparative fluorescence properties of lipoxygenases.
abstract: 1. Lipoxygenases purified from tomato, rat liver and soybean show a fluorescence band centered at 648 nm, which is likely to derive from Tyr and Trp. 2. The intensity of this fluorescence range from 0.7 to 1.0% of the intensity of their major intrinsic fluorescence band (lambda max = 343 nm) in all these lipoxygenases. 3. At inhibitory concentrations, ditizone partly quenches the fluorescence of the lipoxygenases above 600 nm. 4. Saturating concentrations of linoleic acid produce 79% quenching of the fluorescence at 648 nm of soybean lipoxygenase inactivated by treatment with 1 mM dithiothreitol. From these data we have obtained an apparent Kd for linoleic acid-lipoxygenase complex dissociation of 34 +/- 3 microM. 5. It is suggested that the fluorescence above 600 nm reveals the presence of aromatic amino acids located near or at the catalytic center.
mesh_terms: D000818:Animals; D001665:Binding Sites; D004230:Dithizone / Q000494:pharmacology; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D008084:Lipoxygenase / Q000302:isolation & purification*; D016859:Lipoxygenase Inhibitors; D008099:Liver / Q000201:enzymology; D010944:Plants / Q000201:enzymology; D051381:Rats; D011919:Rats, Inbred Strains; D013025:Glycine max / Q000201:enzymology; D013045:Species Specificity; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity
chemical_list: D016859:Lipoxygenase Inhibitors; D004230:Dithizone; D008084:Lipoxygenase