Premium
Stability of ribonuclease T2 from Aspergillus oryzae
Author(s) -
Kawata Yasushi,
Hamaguchi Kozo
Publication year - 1995
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560040308
Subject(s) - rnase p , ribonuclease , chemistry , guanidine , aspergillus oryzae , rnase h , enzyme , crystallography , biochemistry , rna , gene
The stability of ribonuclease T2 (RNase T2) from Aspergillus oryzae against guanidine hydrochloride and heat was studied by using CD and fluorescence. RNase T2 unfolded and refolded reversibly concomitant with activity, but the unfolding and refolding rates were very slow (order of hours). The free energy change for unfolding of RNase T2 in water was estimated to be 5.3 kcal‐mol −1 at 25 °C by linear extrapolation method. From the thermal unfolding experiment in 20 mM sodium phosphate buffer at pH 7.5, the T m and the enthalpy change of RNase T2 were found to be 55.3 °C and 119.1 kcal‐mol −1 , respectively. From these equilibrium and kinetic studies, it was found that the stability of RNase T2 in the native state is predominantly due to the slow rate of unfolding.