Effects Of Crowding Reagents And Osmolytes On The Phase Transition Characteristics Of Different Topological Structures Of Elastin-like Polypeptides

Elastin-like polypeptides?ELPs?as a well-known temperature-control of biological macromolecules are widely used.However,little is known about the interactions between ELPs and organic macromolecules,which is an important but neglected problem.The crowding reagents and osmolytes solvents were used to study their effects on the phase transition temperatures of ELPs with different topologies.The phase transition characteristics were investigated by using UV spectro-photometer and fluorescence spectroscopy.It provides basic research for the application of ELPs in complex system in the future,and also provides reference for the study of other disorder structural proteins.The experimental results show that the phase transition characteristics of ELPs with different topological structures are different from those in simple buffer solutions,and the results are as follows:Firstly,in the solution system of osmolytes,with the increase of sucrose concentration,the phase transition temperature of EA+EBE and T-E-F decreased about 2?,and the phase transition temperature of Tadpole-like E was almost unchanged.And with the increase of sorbitol concentration,the phase transition temperature of ELPs in different topologies reduced 2⁴?.Moreover,with the increase of trehalose concentration,the phase transition temperature of different topological structure ELPs reduced 3⁶?.Effects of osmolytes on ELPs transition temperature is trehalose>sorbitol>sucrose,and the effects of the concentration of ELPs on the phase transition temperature is stronger than that of osmolytes.Secondly,the effects of different molecular weight of PEG on 25?mol/L ELP₄₀phase transition temperature were different,with the increase of the molecular weight of PEG,ELP40 phase transition temperature gradually increased,and then deceased,while the effects on the phase transition temperature of 25?mol/L ELP₁₂₀ decreased all the time;With the increase of PEG2000 concentration,the EA+EBE transition temperature decreased 14¹6.6?,T-E-F transition temperature decreased11.9¹7.1?,Tadpole-like E transition temperature decreased 11.5¹6?,among them,25?mol/L Tadpole-like E phase transition was slow;When ELPs concentration was higher,the more phase transition temperature decreases with the the increase of PEG2000 concentration;The tendency of PEG2000 to influence the ELPs phase transition temperature is not much related to the various topological structures of ELPs.Finally,the phase transition characteristics of 25?mol/L E-C in salt?Na₂CO₃,Na2SO4,Na Cl?solution after adding crowding reagents were studied,the results show that the phases transition of E-C occurred at a concentration of lower than 0.5 mol/L Na₂CO₃/PEG2000,while in single Na₂CO₃?<0.5 mol/L?,the phase transition of EA didn't occur.In Na2CO3/PEG solution,we observed a unique two-step phase transition of E-C when Na2CO3 concentration increased to 0.5 mol/L and PEG2000concentration is less than 0.15 g/mL.In the o.5 mol/L Na₂CO₃/PEG2000 solution,the phase-transition temperature of EA decreased 44?with the increase of PEG concentration,but it increased 22?in the Na₂SO₄/PEG2000 solution,while it remained 33?in the NaCl/PEG2000 solution.However,the phase-transition temperature of the linear ELP₄₀ decreased under the same salts/PEG2000 solutions.