ISSN:
1432-1912
Keywords:
Kininogens
;
Kallikreins
;
Bradykinin
;
Protease Inhibitors
;
Hageman Factor
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 1. Prekallikrein, prepared according to Nagasawaet al., has been purified further by agarose gel electrophoresis. It can be activated directly by Hageman factor and by solid phase trypsin. Its specific activity (benzoyl arginine ethyl ester as substrate) was 13.2 μM min−1 mg−1. Gel filtration on a calibrated column of sephadex G 200 revealed a molecular weight of 101,000, which is close to the value reported for casein-activated kallikrein. 2. The contact-activated bovine enzyme was very similar to casein-activated porcine kallikrein. Both enzymes hydrolyzed benzoyl arginine ethyl ester and tosylarginine methyl ester with about the same speed. The sensitivity of the two preparations against trasylol®, soy bean inhibitor, and serum inhibitor was also not different. 3. In contrast to previous assumptions, purified bovine LMW kininogen (MW 50,000) proved to be substrate for contact-activated kallikrein. As with the caseinactivated enzyme, the total bradykinin content of the kininogen could be released. 4. Serum, even when heated previously to 61°C, contains inhibitors against kallikreins activated by contact or casein, as well as against trypsin. Whereas pretreatment according to Diniz and Carvalho (pH about 2; 98°C) renders the serum more susceptible to trypsin, such denaturated substrate is less accessible for both kallikreins. Serum or plasma pretreated according to Horton (pH2; 37°C), yield at least 50% of the kinin activity obtained with trypsin, irrespective of the kallikreins used. 5. When acid-treated (according to Horton) 61°-serum has been incubated first with casein-activated kallikrein, contact-activated enzyme does not release additional kinin activity and vice versa. 6. Plasma which has been rotated exhaustively with glass, nevertheless contains substrate for contact-activated kallikrein. 7. Addition of Hageman factor to Horton's substrate does not increase the kinin yield above that obtained by glass-contact of normal plasma. Addition of prekallikrein, however, increases the kinin yield about threefold. Therefore, neither Hageman factor nor substrate, but the actual amount of active kallikrein limits the kinin yield upon glass activation. 8. Our experiments with serum kallikreins and their substrates can be interpreted without assuming a distinct, contact activated kinin system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01422018
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