Interaction between duodenase and alpha1-proteinase inhibitor.
The interaction between duodenase, a newly recognized serine proteinase belonging to the small group of Janus-faced proteinases, and alpha1-proteinase inhibitor (alpha1-PI) from human serum was investigated. The stoichiometry of the inhibition was 1.2 mol/mol. The presence of a stable enzyme-inhibitor complex was shown by SDS-PAGE. The mechanism of interaction between duodenase and alpha1-PI was shown to be of the suicide type. The equilibrium and inhibition constants are 13 +/- 3 nM and (1.9 +/- 0.3).105 M-1.sec-1, respectively. Based on the association rate constant of the enzyme-inhibitor complex and localization of duodenase and alpha1-PI in identical compartments, alpha1-PI is suggested to be a duodenase inhibitor in vivo.
Gladysheva
I P
IP
Department of Chemical Enzymology, School of Chemistry, Lomonosov Moscow State University, Moscow, 119899, Russia. gladysheva@enzyme.chem.msu.ru
Popykina
N A
NA
Zamolodchikova
T S
TS
Larionova
N I
NI
D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007700:Kinetics; D011485:Protein Binding; D012697:Serine Endopeptidases / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000378:metabolism*; D013379:Substrate Specificity; D000515:alpha 1-Antitrypsin / Q000378:metabolism*
D015842:Serine Proteinase Inhibitors; D000515:alpha 1-Antitrypsin; D012697:Serine Endopeptidases; C078261:duodenase