We report the biochemical and structural characterization of the purine-specific ribonucleoside hydrolase from the archaeon Sulfolobus solfataricus (SsIAG-NH). SsIAG-NH is a homodimer of 70 kDa specific for adenosine, guanosine and inosine. SsIAG-NH is highly thermophilic and is characterized by extreme thermodynamic stability (Tm, 107 °C), kinetic stability and remarkable resistance to guanidinium chloride-induced unfolding. A disulfide bond that, on the basis of SDS-PAGE is positioned intersubunits, plays an important role in thermal stability. SsIAG-NH shares 43% sequence identity with the homologous pyrimidine-specific nucleoside hydrolase from S. solfataricus (SsCU-NH). The comparative sequence alignment of SsIAG-NH, SsCU-NH, purine non-specific nucleoside hydrolase from Crithidia fasciculata and purine-specific nucleoside hydrolase from Trypanosoma vivax shows that, only few changes in the base pocket are responsible for different substrate specificity of two S. solfataricus enzymes. The structure of SsIAG-NH predicted by homology modeling allows us to infer the role of specific residues in substrate specificity and thermostability.
|Titolo:||Biochemical characterization and homology modeling of a purine-specific ribonucleoside hydrolase from the archaeon Sulfolobus solfataricus: insights into mechanisms of protein stabilization|
|Autori interni:||MARABOTTI, ANNA|
|Data di pubblicazione:||2009|
|Rivista:||ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS|
|Appare nelle tipologie:||1.1.2 Articolo su rivista con ISSN|