The Research On Structural Design And Preliminary Mechanism Of Mimetic Peroxidase

Peroxidase are gotten out from oxido-reductase which catalysis and decomposedoxides，peroxides and other toxic in the body, etc.. We can get the peroxidasemimics which include heme by hydrolyzing peroxidase in vivo, hemoglobicperoxidase which include of metalloporphyrin ring are applied wildly.In ourlaboratory,we designed a new kind of peroxides mimics Deuterohaemin-Ala-His-Thr-Val-Glu-Lys(DhHP-6) which has the ability of catalysis decomposingperoxide and promotes the proliferation of the cell,and increasing the average lifeof C.elegans by about20%in vitro. At the same time, it can improve thenematode C. elegans’ resistance capability of hot pressure and oxidative damageinducing by Paraquat. In the animal experiment,we also find DhHP-6can inhibitthe formation of rats’ cataract. Combining the peroxidase activity of DhHP-6invitro, the most likely explanation is: DhHP-6can change the cell oxidation levelthrough its peroxidase activity directly, or affect cell state by participating in thecell signaling pathways，or both. To further explore the DhHP-6’s mechanism, wereform the structure of DhHP-6. Specifically, using solid phase peptide synthesistechnology, we use sub-porphyrin (porphyrin ring center without iron) connectingwith the six peptides, synthetic peptides are finished，PHP-6.Then we will replacethe histidine which is the second of DhHP-6of β-alanine,DhAP-6.The measuredenzymatic characterization found that the enzyme activity of PHP-6andDhAP-6PHP-6is only about1%of the DhHP-6enzyme activity.Our analysis of spectra from the ultraviolet structure of the porphyrin ring through the UVspectrum,founding that the absorption peak of DhHP-6is387nm while thesub-porphyrin with the six peptides369nm, DhAP-6has twin peaks and themaximum absorption peaks for385nm apparently offset.. Using Circulardichroism to analyze the structural of DhHP-6, PHP-6and DhAP-6, finding thatthere is coordination with iron of the porphyrin ring center and histidine residues.This thesis research the activity of DhHP-6,DhAP-6and PHP-6in vivo,measuring the lifespan by C.elegans, administration the TJ356(daf-16:GFP)mutant elegans DAF-16into the nucleus, as well as the C.elegans changes of freeradicals, to study the DhHP-6as a mimetic enzymestructural meachanisms.The experimental results that DhHP-6-administered with ten days canpromote DAF-16into nuclear in TJ356(daf-16:GFP) mutant elegans; Withthe wild-type C.elegans growth,DhAP-6,PHP-6doesnot clear the nematode freeradicals or increase the expression of SOD,.These composite results suggestedthat the coordination between the histidine residues of the side chain imidazolegroups and the porphyrin ring center iron atoms plays a key role in the peroxidesenzyme activity of DhHP-6.