Physical-chemical characterization and stability study of α-trypsin at pH 3.0 by differential scanning calorimetry

Physical-chemical characterization and stability study of α-trypsin at pH 3.0 by differential scanning calorimetry

α-Trypsin is a serine-protease with a polypeptide chain of 223 amino acid residues and six disulfide bridges. It is a globular protein with predominance of antiparallel ß-sheet secondary structure and it has two domains with similar structures. In the present work, a stability study of α-trypsin in...

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Bibliographic Details
Published in:International journal of biological macromolecules Vol. 42; no. 3; pp. 278 - 284
Main Authors: Santos, A.M.C., Santana, M.A., Gomide, F.T.F., Miranda, A.A.C., Oliveira, J.S., Boas, F.A.S. Vilas, Vasconcelos, A.B., Bemquerer, M.P., Santoro, M.M.
Format: Journal Article
Language:English
Published: Netherlands Elsevier B.V 01-04-2008
Subjects:
Animals
Calorimetry
Calorimetry, Differential Scanning - methods
Enzyme Stability
Hydrogen-Ion Concentration
Isoenzymes - chemistry
Isoenzymes - isolation & purification
Protein Structure, Secondary
Protein Structure, Tertiary
Shelf-life
Thermodynamics
Time Factors
Trypsin - chemistry
Trypsin - isolation & purification
Trypsin isoforms
α-Trypsin
Shelf-life
Thermodynamics
Calorimetry
α-Trypsin
Trypsin isoforms
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Summary:α-Trypsin is a serine-protease with a polypeptide chain of 223 amino acid residues and six disulfide bridges. It is a globular protein with predominance of antiparallel ß-sheet secondary structure and it has two domains with similar structures. In the present work, a stability study of α-trypsin in the acid pH range was performed and some physical-chemical denaturation parameters were measured by using differential scanning calorimetry (DSC). The α-trypsin has a shelf-life ( t 95%) of about 10 months at pH 3.0 and 4 °C and its hydrolysis into the ψ-trypsin isoform is negligible during 6 months. The observed ratio Δ H cal/Δ H vH is close to unity, which suggests the occurrence of a two-state transition. At pH 3.0, α-trypsin unfolded with T m = 325.9 K and Δ H = 99.10 kcal mol −1, and the change in heat capacity between the native and unfolded forms of the protein was estimated to be 1.96 ± 0.18 kcal mol −1 K −1. The stability of α-trypsin calculated at 298 K was Δ G U = 6.10 kcal mol −1 at pH 3.0. These values are in the range expected for a small globular protein. These results show that the thermodynamic parameters of unfolding of β-trypsin do not change substantially after its conversion to α-trypsin.
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ISSN:0141-8130
1879-0003
DOI:10.1016/j.ijbiomac.2007.12.002