Mechanism of the Immunohematologic Effect of Papain and Related Enzymes

Open Access
Publisher Website
Google Scholar
Abstract
Summary: The mechanism has been studied by which papain, bromelin, and ficin produce their effect on red blood cells to render them specifically agglutinable by nonsaline agglutinating Rh antisera. The serologically active enzymes are proteolytic and have common specificity in that each catalyzes hydrolysis of derivatives of the basic amino acids arginine and lysine. However, thrombin and plasmin, which share this specificity, are serologically inactive. Investigation by paper chromatography of supernatants from red cells incubated with papain failed to reveal peptides that might result from proteolytic action of enzyme on the cells. Contacting nonsaline agglutinating antibodies with enzymetreated cells does not affect the serologic properties of the antibodies and further indicates that only the cells are affected by the enzyme. Studies with papain-I131 indicate that a significant portion of the enzyme remains firmly bound to the cells after only 2-min incubation. The amount bound was not increased by extending incubation time to 30 min. Nonactivated and p-(chloromercuri)-benzoic acid (PCMB)-inhibited papain are also bound to the cells but without producing the serologic reaction. When papain bound in this way is treated with cysteine and ethylenediaminetetracetic acid (EDTA), activation occurs with consequent production of the serologic effect. Hypotheses concerning the mechanism by which the serologic effect is produced are offered.