title: Structure of a post-translationally processed heterodimeric double-headed Kunitz-type serine protease inhibitor from potato.
abstract: Potato serine protease inhibitor (PSPI) constitutes about 22% of the total amount of proteins in potato tubers (cv. Elkana), making it the most abundant protease inhibitor in the plant. PSPI is a heterodimeric double-headed Kunitz-type serine protease inhibitor that can tightly and simultaneously bind two serine proteases by mimicking the substrate of the enzyme with its reactive-site loops. Here, the crystal structure of PSPI is reported, representing the first heterodimeric double-headed Kunitz-type serine protease inhibitor structure to be determined. PSPI has a β-trefoil fold and, based on the structure, two reactive-site loops bearing residues Phe75 and Lys95 were identified.
authors: Biophysical Structural Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
authors: Elisabeth M
authors: EM
authors: Meulenbroek
authors: Ellen A J
authors: EA
authors: Thomassen
authors: Laurice
authors: L
authors: Pouvreau
authors: Jan Pieter
authors: JP
authors: Abrahams
authors: Harry
authors: H
authors: Gruppen
authors: Navraj S
authors: NS
authors: Pannu
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry*; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D015842:Serine Proteinase Inhibitors / Q000737:chemistry* / Q000302:isolation & purification; D011198:Solanum tuberosum / Q000737:chemistry*
chemical_list: D010940:Plant Proteins; D015842:Serine Proteinase Inhibitors