title: A serine proteinase inhibitor from frog eggs with bacteriostatic activity.
abstract: By Sephadex G-50 gel filtration, Resource Q anionic exchange and C4 reversed phase liquid high performance liquid chromatography, a proteinase inhibitor protein (Ranaserpin) was identified and purified from the eggs of the odour frog, Rana grahami. The protein displayed a single band adjacent to the molecular weight marker of 14.4 kDa analyzed by SDS-PAGE. The inhibitor protein homogeneity and its molecular weight were confirmed again by MALDI-TOF mass spectrometry analysis. The MALDI-TOF mass spectrum analysis gave this inhibitor protein an m/z of 14422.26 that was matched well with the result from SDS-PAGE. This protein is a serine proteinase inhibitor targeting multiple proteinases including trypsin, elastase, and subtilisin. Ranaserpin inhibited the proteolytic activities of trypsin, elastase, and subtilisin. It has an inhibitory constant (K(i)) of 6.2 x 10(-8) M, 2.7 x 10(-7) M and 2.2 x 10(-8) M for trypsin, elastase, and subtilisin, respectively. This serine proteinase inhibitor exhibited bacteriostatic effect on Gram-positive bacteria Bacillus subtilis (ATCC 6633). It was suggested that ranaserpin might act as a defensive role in resistance to invasion of pests or pathogens. This is the first report of serine proteinase inhibitor and its direct defensive role from amphibian eggs.
authors.affiliation: College of Life Sciences School of Heibei Normal University, Shijiazhuang, Hebei, 050016 China.
authors.forename: Yaoping
authors.initials: Y
authors.lastname: Han
authors.forename: Haining
authors.initials: H
authors.lastname: Yu
authors.forename: Xinbo
authors.initials: X
authors.lastname: Yang
authors.forename: Huw H
authors.initials: HH
authors.lastname: Rees
authors.forename: Jingze
authors.initials: J
authors.lastname: Liu
authors.forename: Ren
authors.initials: R
authors.lastname: Lai
mesh_terms: D029845:Amphibian Proteins; D000818:Animals; D005260:Female; D008970:Molecular Weight; D009865:Oocytes / Q000737:chemistry*; D011898:Ranidae; D012697:Serine Endopeptidases / Q000737:chemistry; D015842:Serine Proteinase Inhibitors / Q000737:chemistry* / Q000302:isolation & purification*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization