scholarly journals The mechanism of interactions between tea polyphenols and porcine pancreatic alpha-amylase: Analysis by inhibition kinetics, fluorescence quenching, differential scanning calorimetry and isothermal titration calorimetry

2017 ◽  
Vol 61 (10) ◽  
pp. 1700324 ◽  
Author(s):  
Lijun Sun ◽  
Michael J. Gidley ◽  
Frederick J. Warren
Keyword(s):  
Differential Scanning Calorimetry ◽  
Fluorescence Quenching ◽  
Isothermal Titration Calorimetry ◽  
Tea Polyphenols ◽  
Alpha Amylase ◽  
Titration Calorimetry ◽  
Inhibition Kinetics ◽  
Scanning Calorimetry

scholarly journals Calorimetric techniques applied to the thermodynamic study of interactions between proteins and polysaccharides

2016 ◽  
Vol 46 (8) ◽  
pp. 1491-1497
Author(s):  
Monique Barreto Santos ◽  
Bernardo de Sá Costa ◽  
Edwin Elard Garcia Rojas
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermodynamic Parameters ◽  
Isothermal Titration Calorimetry ◽  
Thermal Energy ◽  
Titration Calorimetry ◽  
Biological Macromolecules ◽  
Valuable Insight ◽  
Scanning Calorimetry ◽  
Temperature Scanning ◽  
Insight Into

ABSTRACT: The interactions between biological macromolecules have been important for biotechnology, but further understanding is needed to maximize the utility of these interactions. Calorimetric techniques provide information regarding these interactions through the thermal energy that is produced or consumed during interactions. Notable techniques include differential scanning calorimetry, which generates a thermodynamic profile from temperature scanning, and isothermal titration calorimetry that provide the thermodynamic parameters directly related to the interaction. This review described how calorimetric techniques can be used to study interactions between proteins and polysaccharides, and provided valuable insight into the thermodynamics of their interaction.

scholarly journals Calorimetric Studies of Melanotransferrin (p97) and Its Interaction with Iron

2005 ◽  
Vol 280 (16) ◽  
pp. 15735-15741 ◽  
Author(s):  
A. Louise Creagh ◽  
Jacqueline W. C. Tiong ◽  
Mei Mei Tian ◽  
Charles A. Haynes ◽  
Wilfred A. Jefferies
Keyword(s):  
Differential Scanning Calorimetry ◽  
Isothermal Titration Calorimetry ◽  
Binding Constant ◽  
Direct Determination ◽  
Molar Ratio ◽  
Titration Calorimetry ◽  
Iron Binding ◽  
Scanning Calorimetry ◽  
Binding Characteristics ◽  
Apparent Binding Constant

The mammalian molecule melanotransferrin (mTf), also called p97, is a member of the transferrin family of molecules. It exists in both secreted and glycosylphosphatidylinositol-anchored forms and is thought to play a role in angiogenesis and in transporting iron across the blood brain barrier. The binding affinity of iron to this molecule has not been formally established. Here, the binding of ferric ion (chelated with a 2-fold molar ratio of nitrilotriacetate) to mTf has been studied using isothermal titration calorimetry and differential scanning calorimetry. One iron-binding site was determined for mTf with similar binding characteristics to other transferrins. In the absence of bicarbonate, binding occurs quickly with an apparent association constant of 2.6 × 107m–1at 25 °C. The presence of bicarbonate introduces kinetic effects that prevent direct determination of the apparent binding constant by isothermal titration calorimetry. Differential scanning calorimetry thermograms of mTf unfolding in the presence and absence of iron were therefore used to determine the apparent binding constant in the bicarbonate-containing system; at pH 7.5 and 25 °C, iron binding occurs in a 1:1 ratio with aKappof 4.4 × 1017m–1. This affinity is intermediate between the high and low affinity lobes of transferrin and suggests that mTf is likely to play a significant role in iron transport where the high affinity lobe of transferrin is occupied or where transferrin is in proportionally low concentrations.

scholarly journals Interaction of plant alkaloid, berberine, with zwitterionic and negatively charged phospholipid bilayers

2011 ◽  
Vol 34 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Justyna Gąsiorowska ◽  
Olga Wesołowska ◽  
Krystyna Michalak
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Fluorescence Quenching ◽  
Electrostatic Interactions ◽  
Phospholipid Bilayers ◽  
Scanning Calorimetry ◽  
Double Peak ◽  
Pharmacological Activities ◽  
First Time ◽  
Thermotropic Properties

Interaction of plant alkaloid, berberine, with zwitterionic and negatively charged phospholipid bilayers Berberine exhibits many pharmacological activities e.g. antibacterial, anti-inflammatory, antiproliferative and apoptosis-inducing. Interaction of berberine with model membranes was studied for the first time using differential scanning calorimetry, fluorescence spectroscopy and turbidity measurements. Influence of berberine on thermotropic properties of bilayers formed from zwitterionic DMPC was insignificant, whereas in bilayers formed from negatively charged DMPG berberine reduced the temperature and cooperativity of main phospholipid phase transition. In higher concentrations berberine induced complex double-peak transition, with the new peak appearing in temperature higher than the original one. It suggested the interaction of the alkaloid with lipid headgroup region of the bilayer. Additionally, berberine quenched fluorescence of Prodan to a higher extent than Laurdan that pointed to stronger interaction with membrane segments close to its surface. Berberine-induced fluorescence quenching of both probes was more pronounced in DPPG than in DPPC bilayers. It was concluded that electrostatic interactions governed berberine association with model membrane.

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