Study On NaDc-ferritin Embedment Of Active Peptide AHLL From Loach And Intestinal Absorption

In this study,we studied Horse spleen spleen deferritin,HSF)and Sodium deoxycholate(NaDC)were used as nanoscale encapsulation carriers to encapsulate the Angiotensin converting enzyme(Angiotensin converting enzyme,Al-His-Leu-Leu(AHLL)was used to study the effect of AHLL and NaDC on HSF structure by UV,fluorescence and circular two-spectrum.On this basis,we studied the effect of ferritin encapsulation on the stability of AHLL and the inhibitory activity of angiotensin converting enzyme(ACE)during oral and gastrointestinal digestion in vitro,and carried out the cell transport experiment of composite nanoparticles(HSF-NaDC-AHLL).The conclusions are as follows:(1)The encapsulation conditions of HSF-NaDC-AHLL composite nanoparticles were obtained: the concentration of carrier protein HSF was 1.5 ?m,the molar concentration of polypeptide AHLL was 0.4 m M,and the molar concentration of NaDC was 0.2 m M.Under these conditions,the encapsulation rate of composite nanoparticles was the best.Based on the particle size and potential of the composite nanoparticle carrier,it is confirmed that HSF-NaDC-AHLL composite nanoparticle has the characteristics of stable system.Electron microscope results showed that the shape of cassia rice grains was spherical,and the polypeptide AHLL was occupied in the cavity of ferritin.According to the top view and3 D view of AFM,the composite nanoparticles presented irregular spherical distribution.The average height was 46.035 nm,the maximum peak depth was 140 nm,the minimum peak depth was 138.369 nm,and the height was about 147.9 nm.The results indicated that the nanoparticle system was successful in embedding.(2)AHLL transport significantly reduced the ?-helix structure and ?-corner structure of HSF,while the content of ?-folded structure and random coilings increased.The above changes in the secondary structure of HSF indicated that the overall molecular conformation of HSF was transformed from order to disorder,and the corresponding functions were also changed.The thermal stability,p H stability and UV stability of HSF-NaDC-AHLL were significantly higher than those of free AHLL.HSF-NaDC-AHLL composite nanoparticles have macromolecular conjugated structures similar to ferritin,and AHLL is embedded into the cavity of ferritin,and the surface properties of ferritin are not changed.The fluorescence intensity of HSF-NaDC-AHLL composite nano-transport system with the addition of sodium deoxycholate was reduced to a certain extent,which may indicate that the electrostatic combination of sodium deoxycholate and HSF slightly changed the molecular structure of HSF,but it did not have a significant impact.(3)After simulated oral,stomach and intestinal digestion,the final degradation rate of AHLL was 51.4%,the final degradation rate of HSF-AHLL was 56.77%,and the final degradation rate of HSF-NaDC-AHLL was 47.78%.In the oral digestion stage,the ACE inhibition rate increased first and then decreased.When the digestion time reached 20 min,the ACE inhibition rate of the corresponding AHLL and HSF-AHLL reached the peak value of 43.5% and 36.7%,respectively.The ACE inhibition rate of HSF-NaDC-AHLL reached the peak value of 32.63% at 25 min.At 125 min,the inhibition rate of AHLL on ACE was 83.22%,while the inhibition rate of HSF-AHLL and HSF-NaDC-AHLL on ACE was 62.97% and 72.1%,respectively,after simulated gastric digestion.(4)Under the concentration of 50 ?g/m L-150 ?g/m L,the absorption of AHLL was obvious.When the concentration increased to 200 ?g/m L,the Papp values of forward and reverse transport decreased,indicating that the transport of AHLL was directional,and the absorption effect was greater than the efferent effect.HSF-NaDC-AHLL has a certain dependence in different p H media,and the transport effect is the best when the p H value of the liquid supply is neutral environment 7.4.In HSF-NaDC-AHLL nanoparticles,the final concentration of AHLL was 150 ?g/m L,and the transport permeability coefficient was the highest under the conditions of p H 7.4 and temperature 37?.The main transport mode of composite nanoparticles HSF-NaDC-AHLL on the monolayer of Caco-2 cells is bypassing transport,and the transmembrane transport of NaDC on the monolayer of Caco-2 cells can effectively open the cell pathway to promote the transport of nanoparticles on the monolayer of Caco-2 cells.