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WY Chen

Publications and source records attributed to WY Chen.

6 recordsLinked to original sources
PubMed2000

Isothermal Titration Microcalorimetric Studies of the Effect of Temperature on Hydrophobic Interaction between Proteins and Hydrophobic Adsorbents.

This study attempted to comprehend how temperature affects hydrophobic interaction between proteins and hydrophobic adsorbents. By equilibrium batch analysis, we measured the adsorption isotherm to evaluate the protein-adsorbent affinity, while isothermal titration calorimetry was used to measure the adsorption enthalpy. In addition, the affinity and enthalpy differences between two proteins, alpha-chymotrypsinogen A and trypsinogen, with two adsorbents, butyl-Sepharose and octyl-Sepharose gel, under varying temperatures were studied with respect to the exposed hydrophobic segments of the protein and ligand hydrophobicity. The enthalpies obtained in this investigation can be used to more thoroughly understand the hydrophobic interaction between proteins and adsorbents. First, the adsorption isotherm experiments reveal that the adsorption quantity of the proteins with the Sepharose gels increases with temperature. For a microcalorimetric measurement, as temperature is increased from 298 to 310 K, the DeltaH value of alpha-chymotrypsinogen A with butyl-Sepharose increases, while the DeltaH value of trypsinogen is reduced. This is likely due to the fact that alpha-chymotrypsinogen A has a higher area of exposed hydrophobic segments than trypsinogen does. This observation also implies that as temperature increases, the interaction mechanism of alpha-chymotrypsinogen A with butyl-Sepharose changes from an adsorption-dominated process to a partitioning process. In addition, for octyl-Sepharose, the DeltaH value of alpha-chymotrypsinogen A is positive and decreases with temperature increment. However, the DeltaH value of trypsinogen was positive and increased with temperature. Therefore, we conclude that as temperature increases, the interaction mechanism of the proteins for octyl-Sepharose is a partitioning-dominated process. Copyright 2000 Academic Press.

Journal Article↗
PubMed1999

Microcalorimetric Studies of the Interactions of Lysozyme with Immobilized Metal Ions: Effects of Ion, pH Value, and Salt Concentration.

This study extends previous research on the interaction of biomaterials with immobilized Cu(II) by isothermal titration calorimetry (ITC) on Fe(III). The difference of the binding behavior of protein with that of the immobilized metal ions is also discussed. For the immobilized Fe(III), ITC results show that the adsorption enthalpy at a constant pH value decreased as the NaCl concentration increased and also decreased with the pH values at constant NaCl concentrations. The adsorption enthalpy become negative under higher pH values or higher salt concentrations indicating the adsorption process is partly driven by the enthalpy. The enthalpy of lysozyme with Fe(III) is higher than that with Cu(II) implying that the heat required for the dehydration of Cu(II) is lower than for the dehydration of Fe(III) and/or that the heat generated from the formation of the coordination with Cu(II) is higher than with Fe(III). In addition, the comparison of different immobilized metal ions corresponding to the equilibrium binding affinity suggests that the binding force of lysozyme with Cu(II) is higher than with Fe(III). This study presents the chemical differences between the binding affinity and the adsorption enthalpy of lysozyme interacting with the immobilized metal ions. The binding and thermodynamic data presented in this study elucidate the mechanism and process of lysozyme binding with immobilized metal ions. In addition, the thermodynamic characteristic functions provide valuable information enabling a more thorough understanding of protein adsorption at the immobilized metal ion affinity surface. Copyright 1999 Academic Press.

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PubMed1997

Microcalorimetric Studies of the Interactions of Lysozyme with Immobilized Cu(II): Effects of pH Value and Salt Concentration

In this investigation, employing a highly sensitive microcalorimeter, we measure the influence of pH value and salt concentration on the heat of interaction between lysozyme and CS-IDA-Cu(II) gel. The direct enthalpy measurement of the interaction provides thermodynamic information regarding the binding behavior of lysozyme toward the immobilized metal ion. The binding enthalpy altered by adsorbed lysozyme at various pH values and salt concentrations are measured. The findings, along with the reported binding isotherm, are discussed herein.

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