Recombinant sporamin and its synthesized peptides with antioxidant activities in vitro

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Title:	Recombinant sporamin and its synthesized peptides with antioxidant activities in vitro
Authors:	Huang, Guan-Jhong Chen, Hsien-Jung Chang, Yuan-Shiun Sheu, Ming-Jyh Lin, Yaw-Huei
Contributors:	園生系
Keywords:	antioxidant activity recombinant protein gene expression sporamin sweet potato
Date:	2007
Issue Date:	2009-11-13 14:31:59 (UTC+8)
Abstract:	Recombinant sporamin B overproduced in E. coli (M15) was purified by Ni2+-chelated affinity chromatography.. The molecular mass of sporamin B is ca. 26 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Total antioxidant status, 1,1-dipheny-2-picrylhydrazyl (DPPH) staining, reducing power method, Fe2+-chelating ability, ferric thiocyanate (FTC) method, and protecting calf thymus DNA against hydroxyl radical-induced damage were studied. The sporamin B protein with a concentration of 100 mu g/mL exhibited highest activity (expressed as 4.21 +/- 0.0078 mM Trolox equivalent antioxidative value, TEAC) in total antioxidant status test. In the DPPH staining sporamin B appeared as a white spot when the concentration was diluted to 25 mg sporamin B/mL (with an absolute amount of 75 pg). Like total antioxidant status, the reducing power, Fe2+-chelating ability, FTC activity and protection calf thymus DNA against hydroxyl radical-induced damage all showed that sporamin B polypeptides have significant antioxidant activities. It was found that antioxidant activities of sporamin B increased from 19% (0 h) to about 29% (24 h) after 24 h hydrolysis by pepsin. Smaller peptides increased with hydrolytic times. Eight peptides for testing antioxidative activity were synthesized according to peptic hydrolysis simulation. The obtained SNIP, VRL, SYCQ, GTEKC, RF, VKAGE, AH, KIEL showed IC50 values of 8.36, 4.23, 0.206, 0.0884, 9.72, 14.9, 13.8 and 24.9 mM, respectively, when scavenging activity of DPPH radicals (%) was measured. These findings mean that cysteine residue is most important in antiradical activities. It was suggested that sporamin B might contribute to its antioxidant activities against hydroxyl and peroxyl radicals.
Relation:	BOTANICAL STUDIES Volume: 48 Issue: 2 Pages: 133-140
Appears in Collections:	[Department of Horticulture] journal articles

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