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There are many ways in which the action of proteolytic enzymes may be controlled by the living organism. One form of control employs proteinase inhibitors, a group of polypeptides, proteins, and glycoproteins. These inhibitors occur in numerous plants and animals. Their methods of isolation are discussed briefly. The inhibitors are differentiated with regard to their mode of action -permanent, temporary, and progressive inhibition -also with regard to their specificity and some physicochemical properties. In the case of temporary inhibition a distinct peptide bond in the reactive site of the inhibitor is split by the respective enzyme. The elucidation of the three dimensional structure of the polyvalent basic inhibitor from bovine lung offers another opportunity to clarify the molecular mechanism of the enzyme -inhibitor reaction. Our present knowledge of their physiological significance is discussed with respect to various inhibitors. The growth retarding effect in experimental animals which are fed leguminosae is partly caused by proteinase inhibitors. Recent experiments show that the inhibitors in solanaceae are a reserve protein, which is not degraded enzymatically and which is found in different plant tissues depending on the state of development of the plant. Furthermore a protective function of the inhibitors is discussed. The physiological significance of the inhibitor from vesiculary glands and from sperm plasma is the best known compared with other mammalian inhibitors. This inhibitor is involved in the process of decapacitation by complex formation with the acrosomal enzyme acrosin of spermatozoa. The biosynthesis of this inhibitor is hormone dependent. In the human female cervical secretion, an inhibitor has been demonstrated, which may influence the sperm migration through the cervix. Possibly an inhibitor from colostrum protects colostral immune bodies from undue degradation in the gastrointestinal tract of the newborn. The primary structure of the bovine colostrum inhibitor resembles that of the polyvalent basic bovine inhibitor to a fairly high degree. The inhibitor from nasal and bronchial mucous membranes, from lacrimal glands, and from submandibularis glands are thought to have a protective function for the inner body surface mainly against bacterial and leucocytic proteinases. This may also be the function of mingin, the inhibitor which is excreted with the urine. A few results indicate that inhibitors from skin also have a protective function. The inhibitors from serum are potent factors in the regulation of coagulation and fibrinolysis. High concentration, a broad inhibition spectrum, and different mechanisms of action of the 6 known serum inhibitors provide a high security against an unphysiological activation of the enzymes of coagulation and fibrinolysis.Der Organismus bedient sich zur Kontrolle der Wirkung proteolytischer Enzyme unter anderem der Proteinaseinhibitoren, einer Gruppe von Polypeptiden, Proteinen und Glycoproteinen. Diese Inhibitoren sind im Pflanzen-und Tierreich weit verbr...

Recent aspects of kinin research. Potentiation and blocking of biological kinin activityThe search for substances that influence the biological activity of the plasma kinins is of great experimental and clinical-therapeutic interest. The first review of this series deals with the potentiating or sensitising action of proteolytic enzymes, tryptic peptides, fibrinopeptides, bradykinin-potentiating factor from snake venom, antifibrinolytics and histamine synergists. The mechanism of action of these substances is discussed. Enzymes appear to act by the enzymic alteration of the kinin receptors. Measurements of the plasma kininogen concentration with the aid of trypsin can be invalidated by peptides that are formed with the bradykinin. The investigations reported in this field are also relevant to the question of the involvement of kinins in physiological and pathological processes.Pksmakinine sind 33 Jahre nach ihrer Entdeckung zu-durch eine Hemmung des Kininabbaus und durch Einsamrnen mit den sie freilegenden und hemmenden Wirkung potenzierender Substanzen am Ort der KininMechanismen zu einem großen Arbeitsgebiet angewacb-Wirkung. Hier sei nur die zweite Gruppe behandelt sen. Kinine besitzen schon in niedrigster Konzentration (Übersicht über Kininasehemmung s. (2)

Recent aspects of kinin research. Potentiation and blocking of biological kinin activityThe search for substances that influence the biological activity of the plasma kinins is of great experimental and clinical-therapeutic interest. The first review of this series deals with the potentiating or sensitising action of proteolytic enzymes, tryptic peptides, fibrinopeptides, bradykinin-potentiating factor from snake venom, antifibrinolytics and histamine synergists. The mechanism of action of these substances is discussed. Enzymes appear to act by the enzymic alteration of the kinin receptors. Measurements of the plasma kininogen concentration with the aid of trypsin can be invalidated by peptides that are formed with the bradykinin. The investigations reported in this field are also relevant to the question of the involvement of kinins in physiological and pathological processes.Pksmakinine sind 33 Jahre nach ihrer Entdeckung zu-durch eine Hemmung des Kininabbaus und durch Einsamrnen mit den sie freilegenden und hemmenden Wirkung potenzierender Substanzen am Ort der KininMechanismen zu einem großen Arbeitsgebiet angewacb-Wirkung. Hier sei nur die zweite Gruppe behandelt sen. Kinine besitzen schon in niedrigster Konzentration (Übersicht über Kininasehemmung s. (2)