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SOME PROPERTIES OF THE PEPSIN NATURAL INHIBITOR
EXTRACTED FROM THE MARINE GASTROPODE Rapana 
thomasiana  GROSSE
 
Natalia Rosoiu 1), M. Serban 2), and Maria Panait 1) 
 
1) Institut Roumain de Recherches Marines Constanta
2) Faculty of Veterinary Medicine Bucuresti


Abstract
A natural inhibitor of pepsin, developing an intensive antipeptic
activity, was separated and purified from the marine gastropode
Rapana thomasiana Grosse; the value the inhibition constant, Ki,
is only 0,009 mg/ml. This inhibitor is of peptidic nature, reacts
almost instantaneously with the enzyme and causes an inhibition of
the noncompetitive type as related to the hemoglobin used as a 
substrate. The inhibition developed is a function of the inhibitor
concentration in the reaction medium and does not depend on the
purity of the preparation used.