Cysteine-independent activation/inhibition of heme oxygenase-2.
Reactive thiols of cysteine (cys) residues in proteins play a key role in transforming chemical reactivity into a biological response. The heme oxygenase-2 (HO-2) isozyme contains two cys residues that have been implicated in binding of heme and also the regulation of its activity. In this paper, we address the question of a role for cys residues for the HO-2 inhibitors or activators designed in our laboratory. We tested the activity of full length recombinant human heme oxygenase-2 (FL-hHO-2) and its analog in which cys265 and cys282 were both replaced by alanine to determine the effect on activation by menadione (MD) and inhibition by QC-2350. Similar inhibition by QC-2350 and almost identical activation by MD was observed for both recombinant FL-hHO-2s. Our findings are interpreted to mean that thiols of FL-hHO-2s are not involved in HO-2 activation or inhibition by the compounds that have been designed and identified by us. Activation or inhibition of HO-2 by our compounds should be attributed to a mechanism other than altering binding affinity of HO-2 for heme through cys265 and cys282.
Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
Dragic
D
Vukomanovic
Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
Mona N
MN
Rahman
Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
Mahin D
MD
Maines
Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
Terence Rs
TR
Ozolinš
Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
Walter A
WA
Szarek
Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
Zongchao
Z
Jia
Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
Kanji
0000-0002-8087-8352
K
Nakatsu
HO-2 activator; HO-2 inhibitor; Heme degradation; QC-2350; heme oxygenase-2; in vitro; menadione; thiols