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Effects of Polyamines on Proline Endopeptidase Activity in Rat Brain
Author(s) -
Soeda Shinji,
Yamakawa Naomi,
Shimeno Hiroshi,
Nagamatsu Atsuo
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb00654.x
Subject(s) - spermidine , spermine , putrescine , polyamine , prolyl endopeptidase , biochemistry , endopeptidase , enzyme inhibitor , enzyme , chemistry , enzyme assay , biology
The in vitro effects of polyamines on the activity of proline endopeptidase (PEPase) in rat brain cytosol, which contains an endogenous PEPase inhibitor, have been studied. Of the three amines tested (spermine, spermidine, and putrescine), spermine and spermidine markedly enhanced the enzyme activity in brain cytosol. At 6.25 m M spermine or 25 m M spermidine, a 13‐ or 14‐fold enhancement of the enzyme activity was observed. When Mg 2+ was used, an approximately fourfold enhancement of the enzyme activity was observed at 50 m M . The enhancement produced by spermine or spermidine was unaffected by Mg 2+ up to 50 m M . The activity of purified PEPase was only slightly affected by each polyamine, but it was inhibited 50% by 50 m M Mg 2+ . On the other hand, 50% inhibition of the enzyme produced by the purified PEPase inhibitor (M r 7,000; K i 0.67 m M ) was completely restored by addition of 0.7 m M spermine, 3.5 m M spermidine, or 28 m M putrescine. This restoration of inhibition by polyamines was reversed by increasing the inhibitor concentration. These data suggest that polyamines effectively reverse the inhibition of PEPase by its endogenous inhibitor by the reversible formation of a kinetically significant complex. The possible functions of polyamines in the regulation of PEPase in vivo are discussed.