Stability of monomeric Cro variants: Isoenergetic transformation of a type I to a type II -hairpin by single amino acid replacements
The thermodynamic stabilities of three monomeric variants of the bacteriophage Cro repressor that differ only in the sequence of two amino acids at the apex of an engineered -hairpin have been determined. The sequences of the turns are EVK-XX-EVK, where the two central residues are DG, GG, and GT...
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| Format: | Artikel |
| Sprache: | Englisch |
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Cold Spring Harbor Laboratory Press
2025
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| Online-Zugang: | https://repository.auw.edu.bd/handle/123456789/1035 |
| _version_ | 1857448927482085376 |
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| author | MOLLAH, A.K.M.M. |
| author_facet | MOLLAH, A.K.M.M. |
| author_sort | MOLLAH, A.K.M.M. |
| collection | institutional Repository |
| description | The thermodynamic stabilities of three monomeric variants of the bacteriophage Cro repressor that differ
only in the sequence of two amino acids at the apex of an engineered -hairpin have been determined. The
sequences of the turns are EVK-XX-EVK, where the two central residues are DG, GG, and GT, respectively.
Standard-state unfolding free energies, determined from circular dichroism measurements as a function of
urea concentration, range from 2.4 to 2.7 kcal/mole, while those determined from guanidine hydrochloride
range from 2.8 to 3.3 kcal/mole for the three proteins. Thermal denaturation yields van’t Hoff unfolding
enthalpies of 36 to 40 kcal /mole at midpoint temperatures in the range of 53 to 58°C. Extrapolation of the
thermal denaturation free energies with heat capacities of 400 to 600 cal/mole deg gives good agreement
with the parameters determined in denaturant titrations. As predicted from statistical surveys of amino acid
replacements in -hairpins, energetic barriers to transformation from a type I turn (DG) to a type II turn
(GT) can be quite small. |
| format | Article |
| id | 123456789-1035 |
| institution | Asian University for Women |
| language | English |
| publishDate | 2025 |
| publisher | Cold Spring Harbor Laboratory Press |
| record_format | dspace |
| spelling | 123456789-10352026-02-18T06:15:22Z Stability of monomeric Cro variants: Isoenergetic transformation of a type I to a type II -hairpin by single amino acid replacements MOLLAH, A.K.M.M. Cro repressor; hairpin; circular dichroism; protein stability; engineered monomer The thermodynamic stabilities of three monomeric variants of the bacteriophage Cro repressor that differ only in the sequence of two amino acids at the apex of an engineered -hairpin have been determined. The sequences of the turns are EVK-XX-EVK, where the two central residues are DG, GG, and GT, respectively. Standard-state unfolding free energies, determined from circular dichroism measurements as a function of urea concentration, range from 2.4 to 2.7 kcal/mole, while those determined from guanidine hydrochloride range from 2.8 to 3.3 kcal/mole for the three proteins. Thermal denaturation yields van’t Hoff unfolding enthalpies of 36 to 40 kcal /mole at midpoint temperatures in the range of 53 to 58°C. Extrapolation of the thermal denaturation free energies with heat capacities of 400 to 600 cal/mole deg gives good agreement with the parameters determined in denaturant titrations. As predicted from statistical surveys of amino acid replacements in -hairpins, energetic barriers to transformation from a type I turn (DG) to a type II turn (GT) can be quite small. 2025-08-07T10:41:42Z 2025-08-07T10:41:42Z 2003 Article https://repository.auw.edu.bd/handle/123456789/1035 en application/pdf Cold Spring Harbor Laboratory Press |
| spellingShingle | Cro repressor; hairpin; circular dichroism; protein stability; engineered monomer MOLLAH, A.K.M.M. Stability of monomeric Cro variants: Isoenergetic transformation of a type I to a type II -hairpin by single amino acid replacements |
| title | Stability of monomeric Cro variants: Isoenergetic transformation of a type I to a type II -hairpin by single amino acid replacements |
| title_full | Stability of monomeric Cro variants: Isoenergetic transformation of a type I to a type II -hairpin by single amino acid replacements |
| title_fullStr | Stability of monomeric Cro variants: Isoenergetic transformation of a type I to a type II -hairpin by single amino acid replacements |
| title_full_unstemmed | Stability of monomeric Cro variants: Isoenergetic transformation of a type I to a type II -hairpin by single amino acid replacements |
| title_short | Stability of monomeric Cro variants: Isoenergetic transformation of a type I to a type II -hairpin by single amino acid replacements |
| title_sort | stability of monomeric cro variants isoenergetic transformation of a type i to a type ii hairpin by single amino acid replacements |
| topic | Cro repressor; hairpin; circular dichroism; protein stability; engineered monomer |
| url | https://repository.auw.edu.bd/handle/123456789/1035 |
| work_keys_str_mv | AT mollahakmm stabilityofmonomericcrovariantsisoenergetictransformationofatypeitoatypeiihairpinbysingleaminoacidreplacements |