Acrylamide-quenching of Rhizomucor miehei lipase.
Steady-state and time-resolved fluorescence-quenching measurements have been performed to study multitryptophan lipase from filamentous fungus Rhizomucor miehei. Using the steady-state acrylamide fluorescence quenching data and the fluorescence-quenching-resolved-spectra (FQRS) method, the total emission spectrum of native ("closed-lid") lipase has been decomposed into two distinct spectral components accessible to acrylamide. According to FQRS analysis, more quenchable component has a maximum of fluorescence emission at about 352 nm whereas less quenchable component emits at about 332 nm. The redder component participates in about 60-64% of the total lipase fluorescence and may be characterized by the dynamic and static quenching constants equal to K(1) = 3.75 M(-1) and V(1) = 1.12 M(-1), respectively. The bluer component is quenchable via dynamic mechanism with K(2) = 1.97 M(-1). Significant difference in the values of acrylamide bimolecular rate quenching constants estimated for redder and bluer component (i.e., k(q) = 1.2 x 10 (9) M(-1)s (-1) vs. k(q) = 4.3 x 10(8) M(-1) s(-1), respectively), suggests that tryptophan residues in fungal lipase are not uniformly exposed to the solvent.
Stobiecka
Agnieszka
A
Institute of General Food Chemistry, Technical University, Łódź, Poland. astobiec@snack.p.lodz.pl
D020106:Acrylamide / Q000494:pharmacology*; D005656:Fungal Proteins / Q000037:antagonists & inhibitors; D007700:Kinetics; D008049:Lipase / Q000037:antagonists & inhibitors*; D020103:Rhizomucor / Q000201:enzymology*; D013050:Spectrometry, Fluorescence
D005656:Fungal Proteins; D020106:Acrylamide; D008049:Lipase