The effect of the osmolyte trimethylamine N-oxide on the stability of the prion protein at low pH.
A study of the effect of trimethylamine N-oxide on the stability of two recombinant forms of the prion protein PrP, an ovine full-length and a human truncated form, is here reported. Both thermal denaturation and denaturation at room temperature were analyzed at pH values above and below the pKa of trimethylamine N-oxide, which is close to 4.7. Surprisingly, results showed that not only is trimethylamine N-oxide able to decrease PrP thermal stability at low pH but it also acts as a strong denaturant at room temperature. Likely, this destabilization is due to the capability of the cationic form of trimethylamine N-oxide to interact with the protein backbone as well as to weaken electrostatic interactions which are important for PrP fold. These results constitute the first experimental measurement of the effect of trimethylamine N-oxide on PrP stability and provide an unambiguous proof of the destabilizing effect of this osmolyte on PrP at low pH.
Dipartimento delle Scienze Biologiche-Sezione Biostrutture and CNISM, Università degli Studi di Napoli Federico II, Via Mezzocannone 16.I-80134 Napoli, Italy.
Vincenzo
V
Granata
Pasquale
P
Palladino
Barbara
B
Tizzano
Alessandro
A
Negro
Rita
R
Berisio
Adriana
A
Zagari
D000818:Animals; D002942:Circular Dichroism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008744:Methylamines / Q000737:chemistry / Q000494:pharmacology*; D008956:Models, Chemical; D018621:PrPC Proteins / Q000737:chemistry; D018620:PrPSc Proteins / Q000737:chemistry; D011328:Prions / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation / Q000187:drug effects; D011489:Protein Denaturation / Q000187:drug effects; D017433:Protein Structure, Secondary / Q000187:drug effects; D011994:Recombinant Proteins / Q000737:chemistry; D012756:Sheep; D013816:Thermodynamics
D008744:Methylamines; D018621:PrPC Proteins; D018620:PrPSc Proteins; D011328:Prions; D011994:Recombinant Proteins; C005855:trimethyloxamine