title: Kunitz-type trypsin inhibitor with high stability from Spinacia oleracea L. seeds.
abstract: The trypsin inhibitor SOTI was isolated from Spinacia oleracea L. seeds through ammonium sulfate precipitation, Sepharose 4B-trypsin affinity chromatography, and Sephadex G-75 chromatography. This typical Kunitz inhibitor showed remarkable stability to heat, pH, and denaturant. It retained 80% of its activity against trypsin after boiling for 20 min, and more than 90% activity when treated with 6 M guanidine hydrochloride. The formation of stable SOTI-trypsin complex (K(i) = 2.3x10(-6) M) is consistent with significant inhibitory activity of SOTI against trypsin-like proteinases present in the larval midgut of Pieris rapae. Sequences of SOTI fragments showed homology with other inhibitors.
authors.affiliation: Key Laboratory of Bio-resources and Eco-environment of the Ministry of Education, Sichuan University, Chengdu, 610064, PR China.
authors.forename: Zhuang
authors.initials: Z
authors.lastname: Kang
authors.forename: Jia-hong
authors.initials: JH
authors.lastname: Jiang
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Ke
authors.initials: K
authors.lastname: Liu
authors.forename: Lin-fang
authors.initials: LF
authors.lastname: Du
mesh_terms: D000595:Amino Acid Sequence; D006863:Hydrogen-Ion Concentration; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification*; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification*; D017433:Protein Structure, Secondary; D012639:Seeds / Q000737:chemistry*; D018724:Spinacia oleracea / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D013696:Temperature
chemical_list: C053865:Kunitz-type protease inhibitor, plant; D010455:Peptides; D010940:Plant Proteins