Naslov
Still a long way to fully understanding the molecular mechanism of Escherichia coli purine nucleoside phosphorylase

Autori
Štefanić, Zoran ; Mikleušević, Goran ; Narczyk, Marta ; Wielgus-Kutrowska, Beata ; Bzowska, Agnieszka ; Luić, Marija

Izvornik
Croatica chemica acta (0011-1643) 86 (2013), 1; 117-127

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, pregledni rad, znanstveni

Ključne riječi
purine nucleoside phosphorylase; catalysis; cooperativity

Sažetak
The results of several decades of studying the catalytic mechanism of Escherichia coli purine nucleoside phosphorylases (PNP) by solution studies and crystal structure determinations are presented. Potentially PNPs can be used for enzyme-activating prodrug gene therapy against solid tumours because of the differences in specificity between human and E. coli PNPs. Biologically active form of PNP from E. coli is a homohexamer that catalyses the phosphorolytic cleavage of the glycosidic bond of purine nucleosides. Two conformations of the active site are possible after substrate(s) binding: open and closed. A series of determined 3D-structures of PNP binary and ternary complexes facilitated the prediction of the main steps in the catalytic mechanism. For their validation the active site mutants: Arg24Ala, Asp204Ala, Arg217Ala, Asp204Asn and double mutant Asp204Ala/Arg217Ala were prepared. The activity tests confirm that catalysis involves protonation of the purine base at position N7 and give better insight into the cooperativity between subunits in this oligomeric enzyme.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Biologija

POVEZANOST RADA