Influence of pH on the structure and stability of the sweet protein MNEI.
MNEI is a single-chain derivative of the sweet protein monellin that, in recent years, has become an accepted model for studying protein dynamic properties such as folding and aggregation. Although MNEI is very resistant at acidic pH, exposure to neutral or alkaline pH strongly affects its stability. We have performed a thorough NMR study of the dynamic properties of MNEI at different pHs. The results demonstrate that, at physiological temperature, exposure to higher pH increases MNEI flexibility. The changes, originating from a well-defined region in the protein, are transmitted to the whole structure and are likely to be the key for triggering unfolding processes.
Dipartimento di Scienze e Tecnologie, Università del Sannio, Benevento, Italy. rspadacc@unisannio.it.
Roberta
R
Spadaccini
Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Naples, Italy.
Serena
http://orcid.org/0000-0003-4787-0882
S
Leone
Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Naples, Italy.
Michele Fortunato
MF
Rega
BMRZ, Goethe University Frankfurt, Germany.
Christian
C
Richter
Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Naples, Italy. delia.picone@unina.it.
Delia
D
Picone
D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry*; D017510:Protein Folding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D013696:Temperature
D010940:Plant Proteins; C002541:monellin protein, Dioscoreophyllum cumminsii

MNEI
; NMR relaxation; NMR titration; protein dynamics