Difference between revisions of "Part:BBa K3098024"

Latest revision as of 13:02, 21 October 2019

DSAOP(Designed Anti-oxidant Peptides)

Free radicals, such as superoxide anions (O2·-) or hydroxyl radicals (HO·), can cause protein damage and DNA mutations that can initiate several diseases, including coronary heart diseases and diabetes. Antioxidants that can scavenge free radicals and plays an important role in biological systems.An antioxidant peptide derived from Pinctada fucata has great poteintial for scavenging free radicals. However the low rate of enzymatic hydrolysis extraction and purification, as well as the high costs of purifying from Pinctada fucata meat, suggest that this natural and safe antioxidant peptide would not meet industrialized production requirements. Thus we submit a designed AOP that can be easily produced and purified in E.coli, named 'DSAOP'.

Usage and Biology

The sequence of antioxidant peptides isolated from Pinctada fucata meat typically includes 10 to 20 amino acids, which is relatively short and easily degraded by protease or peptidase in Escherichia coli expression systems. Therefore, it is difficult to express these peptides directly. Based on previous reports, an antioxidant peptide from Pinctada fucata meat (amino acid sequence was GAGLPGKRER, named AOP) has high antioxidant activity in vitro, a design containing the GAGLPGKRER sequence was constructed for further expression to obtain a higher yield and improve its stability in our project’s applications in room temperature environment. Meanwhile, solubility of the designed polypeptide were considered.

Sequence and Features

Results

1.Measurement of DPPH Radical Scavenging Activity
The DSAOP antioxidant activity was determined using the DPPH radical scavenging assay. DPPH, also known as 1, 1-diphenyl-2-trinitrophenylhydrazine, is a very stable free radical in the nitrogen center. Its stability mainly comes from the spatial barrier of the three benzene rings with resonance stabilization effect, so that the unpaired electrons on the middle nitrogen atoms cannot play their due electron pairing effect. Its size of anhydrous ethanol was purple in color, with maximum absorption at 517nm wavelength and linear relationship between absorbance and concentration. When free radical scavenger is added to it, DPPH can be combined or replaced to reduce the number of free radicals, reduce the absorbance, and make the solution color become lighter, so as to evaluate the ability of scavenging free radicals. In other words, the antioxidant capacity was calculated by detecting the effect of removing DPPH from the sample at the wavelength of 517nm.The DPPH radical scavenging activity was calculated as follows:
DPPH radical scavenging activity (100%) = [1 − (Ai − Aj )/ A0] × 100.
The following is the result of the DPPH radical scavenging activity of DSAOP compared with DSAOP+Avitag and Vitamin E. The DSAOP has the best scavenging activity and enduring ability.

2.Measurement of Hydroxyl radical scavenging activity
Fenton reaction to generate hydroxyl free radicals react with salicylic acid, generated at 510 nm with special absorption of 2, 3 - dihydroxy benzoic acid, reactive is as follows: if the material join in the reaction system has the function of removing hydroxyl free radical, it will reduce the number of generated hydroxyl free radicals, thus reduce the generation of coloured compounds corresponding. Fixed reaction time was used in method, the absorbance of the reaction solution containing the tested substance was measured at 510 nm and compared with the blank solution to determine the hydroxyl content of the measured substance Clearance of bases.
The following picture is the result of the Hydroxyl radical scavenging activity compared with DSAOP+Avitag and Vitamin E. The DSAOP - Avitag has the best hydroxyl scavenging activity and the next one is DSAOP.

Functional Parameters