Font Size: a A A

Physicochemical Properties Of Proteins At Air/Water Interface And Proteins Monolayer Forming

Posted on:2004-02-09Degree:DoctorType:Dissertation
Country:ChinaCandidate:J HuaFull Text:PDF
GTID:1101360095953667Subject:Materials science
Abstract/Summary:PDF Full Text Request
The problem on physical and chemical behaviors of protein at air/water interface is a one of point of study on"soft mater and soft interface "and a basic subject of membrane-mimetic chemistry, which is significance in understanding the phenomena of condensed phase for biopolymers in quasi-two-dimensional space and also important for preparing the functional materials by use of the "aqueous methods" in colloid chemistry. The adsorption kinetics from the solution to the air/water interface and forming properties of protein monolayers at the interface have been investigated .The viscosity behavior of protein dilute solution, which includes the hydrodynamics molecular dimension of the protein ,intermolecular action force in the dilute solution and other factors, was also studied. Finally, the physicochemical structures of silk from spider Selenocosmia were characterized by means of IR, SEM and AFM. in this dissertation.As protein sample in the experiment , spider protein, silk protein and sericin protein were used. The surface pressure of three proteins at air/water interface, which is cased by adsorption from the solution to the surface and then arranging and orienting at surface, were measured by means of Wilhelmy plate technique. Using Gibbs equation, the surface concentration of the solution can be evaluated. Analyzing the -t relationship of the protein adsorption and A1 and A2 given by 1n(d /dt)- relation curve, the adsorption mechanism for the protein may be predicted. The surface pressure value of the protein was changed with the change of molecular conformation in adsorption surface or the monolayer at air/water interface, which is cased by adding acid, or base, or salt to sub-phase solution. Moreover, the difference of absorption properties for two fibrous proteins, spider protein and silk protein, was analyzed and discussed, respectively.The properties of monolayer forming for the proteins were investigated by using spreading technique on the surface of sub-phase in the Langmuir trough. The -A curve of the different monolayer of the proteins, including spider protein, silk protein and sericin protein, were obtained respectively. The formation conditions, e. g., the diffusion for the proteins at the surface of the solution, the sub-phase of the solution which includes it's pH value, the concentration, and the varieties salt and it's concentration in the solution and, the protein aqueous solution as spreading solution which it's spreading volume and spreading way are varied, have been investigated to determine the optimal processing conditions. The molecular conformation of the proteins varies with the sub-phase condition which is found by the change -A relationship curve for the protein monolayer. The molecular conformation in the protein monolayer was given by -A curve on which several transition points imply phase transitions representing gas/liquid/solid three phases in the monolayer. Comparing and the analyzing the properties of monolayer formation for three proteins, the differences of structure at air/water interface between the fibrous protein for spide protein and sild protein and globular protein for sericin protein nay be found on the -A relationship curve.The intrinsic viscosity [ ]for the dilute proteins solution has been determined and the interaction coefficient between protein molecules, and between protein molecules and solvent maybe evaluated by using Huggins equation. The hydrodynamical dimension characterized by the intrinsic viscosity [ ] was important to know molecular conformations in the dilute solution.The composition of amino acid, the molecular functional groups, the molecular conformation and the morphological structure of fibers for the spider silk were determined by using the analytical instrument for amino acid, IR, SEM and AFM, respectively.The experiments results show that the protein adsorption process consists of two steps, of which one is rapid step controlled by diffusion of protein molecule from solution to surface, and the second st...
Keywords/Search Tags:Protein, Spider protein, Silk protein, Sericin protein, Air/water interface, Adsorption kinetics, Monolayer
PDF Full Text Request
Related items