title: Conversion of cytochrome c into a peroxidase: inhibitory mechanisms and implication for neurodegenerative diseases.
abstract: A further function of cytochrome c (cyt c), beyond respiration, is realized outside mitochondria in the apoptotic program. In the early events of apoptosis, the interaction of cyt c with a mitochondrion-specific phospholipid, cardiolipin (CL), brings about a conformational transition of the protein and acquirement of peroxidase activity. The hallmark of cyt c with peroxidase activity is its partial unfolding accompanied by loosening of the Fe sixth axial bond and an enhanced access of the heme catalytic site to small molecules like H2O2. To investigate the peroxidase activity of non-native cyt c, different forms of the protein were analyzed with the aim to correlate their structural features with the acquired enzymatic activity and apoptogenic properties (wt cyt c/CL complex and two single cyt c variants, H26Y and Y67H, free and bound to CL). The results suggest that cyt c may respond to different environments by changing its fold thus favouring the exertion of different biological functions in different pathophysiological cell conditions. Transitions among different conformations are regulated by endogenous molecules such as ATP and may be affected by synthetic molecules such as minocycline, thus suggesting a mechanism explaining its use as therapeutic agent impacting on disease-associated oxidative and apoptotic mechanisms.
authors.affiliation: Department of Experimental Medicine and Biochemical Sciences, University of Rome TorVergata, via Montpellier 1, 00133 Rome, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Patriarca
authors.forename: Fabio
authors.initials: F
authors.lastname: Polticelli
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Piro
authors.forename: Federica
authors.initials: F
authors.lastname: Sinibaldi
authors.forename: Giampiero
authors.initials: G
authors.lastname: Mei
authors.forename: Monica
authors.initials: M
authors.lastname: Bari
authors.forename: Roberto
authors.initials: R
authors.lastname: Santucci
authors.forename: Laura
authors.initials: L
authors.lastname: Fiorucci
mesh_terms: D000818:Animals; D020169:Caspases / Q000378:metabolism; D002474:Cell-Free System; D002942:Circular Dichroism; D045304:Cytochromes c / Q000037:antagonists & inhibitors / Q000378:metabolism*; D055664:Electrochemical Techniques; D004789:Enzyme Activation; D006736:Horses; D008911:Minocycline / Q000378:metabolism; D008958:Models, Molecular; D010544:Peroxidases / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D045304:Cytochromes c; D010544:Peroxidases; D020169:Caspases; D008911:Minocycline