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The Thermal Stability of the Fusarium solani pisi Cutinase as a Function of pH.

Petersen SB, Fojan P, Petersen EI, Petersen MT - J. Biomed. Biotechnol. (2001)

Bottom Line: The ratio between the calorimetric enthalpy (DeltaH(cal)) and the van't Hoff enthalpy (DeltaH(v)) obtained, is far from unity, indicating that cutinase does not exhibit a simple two state unfolding behaviour.The role of pH on the electrostatic contribution to the thermal stability was assessed using TITRA.We propose a molecular interpretation for the pH-variation in enzymatic activity.

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ABSTRACT
We have investigated the thermal stability of the Fusarium solani pisi cutinase as a function of pH, in the range from pH 2-12. Its highest enzymatic activity coincides with the pH-range at which it displays its highest thermal stability. The unfolding of the enzyme as a function of pH was investigated by microcalorimetry. The ratio between the calorimetric enthalpy (DeltaH(cal)) and the van't Hoff enthalpy (DeltaH(v)) obtained, is far from unity, indicating that cutinase does not exhibit a simple two state unfolding behaviour. The role of pH on the electrostatic contribution to the thermal stability was assessed using TITRA. We propose a molecular interpretation for the pH-variation in enzymatic activity.

No MeSH data available.


Visualization of the electrostatic potential on the surface at 4 different pH values of cutinase. Mapping the calculated partial charges to the surface of cutinase. Each titratable residue was predicted by TITRA. The potential distribution on the cutinase surface was calculated by DelPhi anddisplayed by Grasp. Charge at the surface of the enzyme at pH 4.0, pH 6.0, pH 8.5, and pH 10.0.
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Figure 6: Visualization of the electrostatic potential on the surface at 4 different pH values of cutinase. Mapping the calculated partial charges to the surface of cutinase. Each titratable residue was predicted by TITRA. The potential distribution on the cutinase surface was calculated by DelPhi anddisplayed by Grasp. Charge at the surface of the enzyme at pH 4.0, pH 6.0, pH 8.5, and pH 10.0.

Mentions: The calculated charges, by using TITRA, carried by the titratableresidues of the protein are then supplied to DelPhi [16] in order to calculate the three-dimensional potential grid for the protein at a particular pH value. Based on these grid data from DelPhi, the electrostatic properties were mapped on the molecular surface of cutinase using the program GRASP (Figure 6). This procedure has been done to be able to visualize the location of the charges on the surface of the protein. The program Titra is capable of calculating the pKa values of titratable amino acids very precisely as seen for ubiquitin where the pKa values have been determined experimentally [17].


The Thermal Stability of the Fusarium solani pisi Cutinase as a Function of pH.

Petersen SB, Fojan P, Petersen EI, Petersen MT - J. Biomed. Biotechnol. (2001)

Visualization of the electrostatic potential on the surface at 4 different pH values of cutinase. Mapping the calculated partial charges to the surface of cutinase. Each titratable residue was predicted by TITRA. The potential distribution on the cutinase surface was calculated by DelPhi anddisplayed by Grasp. Charge at the surface of the enzyme at pH 4.0, pH 6.0, pH 8.5, and pH 10.0.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC113781&req=5

Figure 6: Visualization of the electrostatic potential on the surface at 4 different pH values of cutinase. Mapping the calculated partial charges to the surface of cutinase. Each titratable residue was predicted by TITRA. The potential distribution on the cutinase surface was calculated by DelPhi anddisplayed by Grasp. Charge at the surface of the enzyme at pH 4.0, pH 6.0, pH 8.5, and pH 10.0.
Mentions: The calculated charges, by using TITRA, carried by the titratableresidues of the protein are then supplied to DelPhi [16] in order to calculate the three-dimensional potential grid for the protein at a particular pH value. Based on these grid data from DelPhi, the electrostatic properties were mapped on the molecular surface of cutinase using the program GRASP (Figure 6). This procedure has been done to be able to visualize the location of the charges on the surface of the protein. The program Titra is capable of calculating the pKa values of titratable amino acids very precisely as seen for ubiquitin where the pKa values have been determined experimentally [17].

Bottom Line: The ratio between the calorimetric enthalpy (DeltaH(cal)) and the van't Hoff enthalpy (DeltaH(v)) obtained, is far from unity, indicating that cutinase does not exhibit a simple two state unfolding behaviour.The role of pH on the electrostatic contribution to the thermal stability was assessed using TITRA.We propose a molecular interpretation for the pH-variation in enzymatic activity.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
We have investigated the thermal stability of the Fusarium solani pisi cutinase as a function of pH, in the range from pH 2-12. Its highest enzymatic activity coincides with the pH-range at which it displays its highest thermal stability. The unfolding of the enzyme as a function of pH was investigated by microcalorimetry. The ratio between the calorimetric enthalpy (DeltaH(cal)) and the van't Hoff enthalpy (DeltaH(v)) obtained, is far from unity, indicating that cutinase does not exhibit a simple two state unfolding behaviour. The role of pH on the electrostatic contribution to the thermal stability was assessed using TITRA. We propose a molecular interpretation for the pH-variation in enzymatic activity.

No MeSH data available.