Nonhistone protein purified from porcine kidney acts as a suicide substrate inhibitor on furin-like enzyme.
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.
Fei
H
H
State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry, Chinese Academy of Sciences, Shanghai 200031, China.
Li
Y
Y
Wang
L X
LX
Luo
M J
MJ
Ling
M H
MH
Chi
C W
CW
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
D002868:Chromosomal Proteins, Non-Histone; D013381:Subtilisins; D045683:Furin