Ov. Koroleva et al., Temperature-induced changes in copper centers and protein conformation of two fungal laccases from Coriolus hirsutus and Coriolus zonatus, BBA-PROT ST, 1547(2), 2001, pp. 397-407
Citations number
35
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEIN STRUCTURE AND MOLECULAR ENZYMOLOGY
The paper reports on two fungal laccases from Coriolus hirsutus and Coriolu
s zonatus and their type-2 copper-depleted derivatives. Temperature-induced
changes of the copper centers were characterized by optical and electron p
aramagnetic resonance (EPR) spectroscopy, and the overall protein stability
by differential scanning microcalorimetry. The intact enzymes showed highl
y cooperative thermal unfolding transitions at about 90 degreesC. Type-2 co
pper depletion led to uncoupling of the domains characterized by a differen
t melting pattern which resolved three subtransitions. Melting curves monit
ored optically at 290, 340 and 610 nm showed additional transitions below t
hermal unfolding temperature. EPR spectra of the intact laccases showed the
disintegration of the trinuclear copper cluster accompanied by loss of one
of the copper ions and disappearance of the strong antiferromagnetic coupl
ing in the type-3 site at 70 degreesC and above 70 degreesC. The copper cen
ters of type-2 copper-depleted laccase showed reduced thermotolerance. (C)
2001 Elsevier Science B,V. All rights reserved.