Preparation Of Zwitterionic Polymers And Their Effects On Activity Of Pepsin And Lipase

The activity of biological enzymes is easily affected by environmental factors,especially the increase of temperature can lead to the change or destruction of the protein structures or the forms of the peptide bond of the enzyme,which leads to the denaturation of enzyme.Therefore,it is one of the key issues that need to be solved to seek some effective methods to maintain the normal conformation of the enzyme.Zwitterionic polymers have excellent biocompatibility and good hydrophilicity,which help to maintain the normal conformation of the enzyme and increase the activity of the enzyme.In this paper,four different degrees of polysulphobetaine methacrylate polymers(PSBMA)were prepared by free radical polymerization,sulfobetaine methacrylate(SBMA)as monomer and ammonium persulfate-sodium sulfite redox system as initiator system;the structures of PSBMA were characterized by 1H-NMR and GPC,then PSBMA and methacryloxyethyl phosphorylcholine(MPC),sulfobetaine methacrylate(SBMA),carboxybetaine methacrylate(CBMA)were used to study the effects on activity of pepsin and lipase.In this paper,bovine hemoglobin,which was used as substrate,hydrolyzed at different temperatures under the action of pepsin,and the effects of MPC,SBMA,and CBMA on pepsin activity were measured by the Folin method.The results showed that the MPC,SBMA,and CBMA all can increase pepsin activity;when the same amount was added,CBMA had a better effect on the maintenance of pepsin activity,and with the increase of add amount,the better the maintenance of pepsin activity The add amount was 0.18 mmol/mL,the pepsin activity of the added CBMA respectively was 153%and 210%of the added MPC and SBMA.At 37℃,the pepsin activity in the presence of CBMA(0.18 mmol/mL)was 194%of the control after 2 h,177%of the control after 4 h,and 162%of the control after 6 h;at 60℃,the pepsin activity in the presence of CBMA(0.18 mmol/mL)was 453%of the control after 2 h,451%of the control after 4 h,and 330%of the control after 6 h.CBMA has a good effect on maintaining pepsin activity.Olive oil was used as the substrate and hydrolyzed under the action of lipase,and the effects of MPC,SBMA and CBMA on lipase activity were measured by copper soap method.The results showed that the effect of SBMA on lipase activity was better than MPC and CBMA.At 37℃,the lipase relative activity in the presence of SBMA(0.2 mM)was 144%of the control after 12 h,113%of the control after 24 h,116%of the control after 36 h.The effects of PSBMA on lipase activity were studied.The results showed that PSBMA3(DP=150,Mn=45514)with a add amount(0.8 mg·mL-1)had a better effect on lipase activity,and the relative activity was 2.10;At 37℃,the lipase relative activity in the presence of PSBMA3(0.8 mg·mL-1)was 222%of the control after 12 h,189%of the control after 24 h,206%of the control after 36 h.SBMA and PSBMA all have good effects on maintaining lipase activity.This paper explores an effective method to increase the activity of biological enzymes by studying the effects of zwitterions and their polymers on the activity of pepsin and lipase.