title: Characterization of a prolyl endopeptidase from spinach thylakoids.
abstract: A prolyl endopeptidase (PEPase, EC 3.4.21.26) that specifically cleaves the 18-kDa protein of photosystem II was extracted from photosystem II membranes with 1 M NaCl. Proteolytic activity measured with artificial substrates was less than a quarter of that with the protein. Studies on inhibition of the proteolysis by an artificial substrate suggested that the protease recognizes the scissile prolyl bond. The protease was inhibited by CuCl2, but not by diisopropyl fluorophosphate or p-chloromercuriphenylsulfonic acid. These findings suggest that the protease represents a new class of PEPase. The specificity of the enzyme is discussed in relation to the structure of the 18-kDa protein.
authors.affiliation: Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kuwabara
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000201:enzymology; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D010944:Plants / Q000201:enzymology; D000085822:Prolyl Oligopeptidases; D011480:Protease Inhibitors / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011480:Protease Inhibitors; D012697:Serine Endopeptidases; D000085822:Prolyl Oligopeptidases