title: PG-2, a Potent AMP against Pathogenic Microbial Strains,  from Potato (Solanum tuberosum L cv. Gogu Valley) Tubers  Not Cytotoxic against Human Cells.
abstract: In an earlier study, we isolated potamin-1 (PT-1), a 5.6-kDa trypsin-chymotrypsin protease inhibitor, from the tubers of a potato strain (Solanum tuberosum L cv. Gogu Valley). We established that PT-1 strongly inhibits pathogenic microbial strains, but not human bacterial strains, and that its sequence shows 62% homology with a serine protease inhibitor. In the present study, we isolated an antifungal and antibacterial peptide with no cytotoxicity from tubers of the same potato strain. The peptide (peptide-G2, PG-2) was isolated using salt-extraction, ultrafiltration and reverse-phase high performance liquid chromatography (RP-HPLC). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) showed the protein to have a molecular mass of 3228.5 Da, while automated Edman degradation showed the N-terminal sequence of PG-2 to be LVKDNPLDISPKQVQALCTDLVIRCMCCC-. PG-2 exhibited antimicrobial activity against Candida albicans, a human pathogenic yeast strain, and Clavibacter michiganensis subsp. michiganensis, a plant late blight strain. PG-2 also showed antibacterial activity against Staphylococcus aureus, but did not lyse human red blood cells and was thermostable. Overall, these results suggest PG-2 may be a good candidate to serve as a natural antimicrobial agent, agricultural pesticide and/or food additive.
authors: Research Center for Proteineous Materials, Chosun University, Gwangju 501-759, Korea. y_k_park@chosun.ac.kr.
authors: Jin-Young
authors: JY
authors: Kim
authors: Ramamourthy
authors: R
authors: Gopal
authors: Sang Young
authors: SY
authors: Kim
authors: Chang Ho
authors: CH
authors: Seo
authors: Hyang Burm
authors: HB
authors: Lee
authors: Hyeonsook
authors: H
authors: Cheong
authors: Yoonkyung
authors: Y
authors: Park