Title of article :
Thermodynamic Properties of BPTI Variants with Highly Simplified Amino Acid Sequences
Author/Authors :
Atsushi Kato، نويسنده , , Munetaka Yamada، نويسنده , , Shigeyoshi Nakamura، نويسنده , , Shun-ichi Kidokoro، نويسنده , , Yutaka Kuroda، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2007
Pages :
10
From page :
737
To page :
746
Abstract :
We report the first detailed thermodynamic analysis of simplified proteins by differential scanning calorimetry (DSC). The experiments were carried out with five simplified BPTI variants, whose structures and activities have been reported, in which several residues not essential for specifying the tertiary structure were replaced by alanine. In most aspects, the thermodynamics of simplified proteins were very similar to, if not essentially identical with, those of natural proteins. In particular, they undergo a highly cooperative two-state thermal unfolding process with a large enthalpy change, which is a thermodynamic hallmark of the native state of natural globular proteins. Furthermore, the specific enthalpy and entropy changes upon unfolding at 110 °C were close to values invariably observed for small natural globular proteins (55 J g− 1 and ~16 J K− 1 g− 1, respectively). On the other hand, two simplified BPTI variants, BPTI-21 and BPTI-22 (containing 21 and 22 alanine residues), were enthalpically stabilized while entropically destabilized with respect to the reference BPTI-[5,55] molecule. This peculiar type of entropy–enthalpy compensation is in sharp contrast to the usual enthalpy destabilization/entropy stabilization observed in mutational studies of natural proteins. Overall, we conclude that a thermodynamic native state can be achieved by proteins encoded with extensively simplified sequences.
Keywords :
alanine-scanning , information degeneracy , DSC , BPTI , protein stability
Journal title :
Journal of Molecular Biology
Serial Year :
2007
Journal title :
Journal of Molecular Biology
Record number :
1249729
Link To Document :
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