Effect of Charged Short Peptides T7+and T6-on the Activity and Structure of α-Amylase
In this experiment,differently charged short peptides T7+and T6-were used to investigate the mechanism of the change in α-amylase activity and conformation by the positively charged short peptide T7+and the negatively charged short peptide T6.The changes of α-amylase activity and conformation were verified by the determination of relative en-zyme activity,Mie's constant(Km),activation energy and zeta potential after the addition of short peptides to α-amylase system.In order to observe more clearly the effects of different charged short peptides on the conformation of α-amylase,UV absorption spectra,fluorescence spectra,simultaneous fluorescence spectra and circular dichroism spectra were also introduced to further investigate the conformational changes of α-amylase.The results showed that the addition of the charged short peptide into the enzymatic reaction of α-amylase,the positively charged short peptide T7+inhibited the α-amylase enzyme activity,and the relative enzyme activity of α-amylase decreased by 2.40％when the short peptide con-centration was 10-7 g/mL,and also decreased the affinity of α-amylase with soluble starch,increased the activation ener-gy and increased the zeta potential.The negatively charged short peptide T6-promoted the α-amylase enzyme activity,and when the short peptide concentration was 10-7 g/mL,the relative enzyme activity of α-amylase increased by 1.40％,and also made the affinity of α-amylase with soluble starch increase,the activation energy decrease and the zeta poten-tial increase.Spectroscopic analysis showed that different charged short peptides changed the UV-visible absorption spec-trum,fluorescence spectrum and secondary structure of α-amylase to different degrees.It was demonstrated that different charged short peptides could play a role similar to that of electric field,the electric field force generated by the electric field when acting on the proteins contributed to the conformational change of the proteins,and the surface charge of the artificially designed synthetic short peptides affected the distribution of the surface charge of the enzyme,which led to the change of the enzyme activity and conformation.
α-amylasecharged short peptiderelative enzyme activityconformation
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