title: Nonhistone protein purified from porcine kidney acts as a suicide substrate inhibitor on furin-like enzyme.
abstract: OBJECTIVE
  To search and purify a naturally occurring protein inhibitor of the furin-like enzyme from the porcine kidney.
  
  
  METHODS
  Recombinant kexin, a furin-like enzyme, from the yeast secretion expression was used as a target enzyme. The inhibitor component was extracted and purified from the acetone powder of porcine kidney. The inhibitory activity was monitored using a fluorogenic peptide substrate Boc-Arg-Val-Arg-MCA at spectrofluorimeter.
  
  
  RESULTS
  The purified inhibitor component is a basic protein with an isoelectric point over 9.5. Its partial N-terminal sequence of 22 residues was determined, showing a high homology with nonhistone chromosomal protein HMG-17 in which there are four sites composed of dibasic residues, susceptible to be cleaved by the furin-like enzyme. This nonhistone protein could strongly compete with the fluorogenic substrate. However, this nonhistone protein would be degraded as a substrate by kexin if it was incubated with the enzyme for long time before adding the fluorogenic substrate, and subsequently lost its temporary inhibitory activity.
  
  
  CONCLUSIONS
  The nonhistone protein isolated from the porcine kidney functioned as a suicide substrate inhibitor for the furin-like enzyme.
authors.affiliation: State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: H
authors.initials: H
authors.lastname: Fei
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: L X
authors.initials: LX
authors.lastname: Wang
authors.forename: M J
authors.initials: MJ
authors.lastname: Luo
authors.forename: M H
authors.initials: MH
authors.lastname: Ling
authors.forename: C W
authors.initials: CW
authors.lastname: Chi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000302:isolation & purification*; D045683:Furin; D007668:Kidney / Q000737:chemistry*; D008969:Molecular Sequence Data; D013381:Subtilisins / Q000037:antagonists & inhibitors*; D013552:Swine
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D013381:Subtilisins; D045683:Furin