scholarly journals Ligand binding, conformational change and plasma elimination of human, mouse and rat α-macroglobulin proteinase inhibitors

1983 ◽  
Vol 209 (1) ◽  
pp. 99-105 ◽  
Author(s):  
S L Gonias ◽  
A E Balber ◽  
W J Hubbard ◽  
S V Pizzo
Keyword(s):  
Ligand Binding ◽  
Conformational Change ◽  
Trypsin Inhibitor ◽  
Proteinase Inhibitor ◽  
Proteinase Inhibitors ◽  
Soya Bean ◽  
The Other ◽  
Complex Reaction ◽  
Bean Trypsin Inhibitor ◽  
Esterolytic Activity

Rat alpha 1-macroglobulin (alpha 1M), rat alpha 2-macroglobulin (alpha 2M) migrated as single bands on non-denaturing gels when purified by the methods described. All three proteins demonstrated increased mobility after reaction with trypsin. A single saturable pathway rapidly cleared complexes of trypsin and the alpha-macroglobulins of mouse, rat and human from the circulation of mice. None of the native alpha-macroglobulins competed for clearance with the trypsin complexes. [14C]Methylamine incorporation was 4.1, 3.9, 2.6 and 3.2 mol/mol of proteinase inhibitor for human alpha 2M, rat alpha 1M, rat alpha 2M and mouse alpha 2M, respectively. Only rat alpha 2M, the acute-phase alpha-macroglobulin studied, showed no evidence of conformational change when subjected to electrophoresis after reaction with methylamine. The clearance of rat alpha 2M-methylamine was comparable with that of the native molecule. The other alpha-macroglobulin-methylamine complexes cleared faster than the inhibitors that had not reacted. Rat alpha 2M and rat alpha 2M-methylamine bound equivalent quantities of 1251-labelled trypsin (1.01 and 0.96 mol/mol respectively). The soya-bean trypsin inhibitor-resistant esterolytic activity of trypsin bound to rat alpha 2M-methylamine was approx. 90% suppressed compared with proteinase bound to native rat alpha 2M. This suppression was not due to a change in the affinity of soya-bean trypsin inhibitor for the complex. Reaction of rat alpha 2M-methylamine with trypsin resulted in a ‘slow’ to ‘fast’ electrophoretic conversion of the proteinase inhibitor, and exposure of the signal on the alpha 2M that causes the complex to clear from the murine circulation.

scholarly journals Functional modifications of α2-macroglobulin by primary amines. Kinetics of inactivation of α2-macroglobulin by methylamine, and formation of anomalous complexes with trypsin

1982 ◽  
Vol 201 (1) ◽  
pp. 119-128 ◽  
Author(s):  
Fred Van Leuven ◽  
Jean-Jacques Cassiman ◽  
Herman Van Den Berghe
Keyword(s):  
Conformational Change ◽  
Trypsin Inhibitor ◽  
Binding Capacity ◽  
Soya Bean ◽  
Primary Amines ◽  
Slow Phase ◽  
Subunit Structure ◽  
Α2 Macroglobulin ◽  
Bean Trypsin Inhibitor ◽  
Kinetics Of

The unique steric inhibition of endopeptidases by human α2M (α2-macroglobulin) and the inactivation of the latter by methylamine were examined in relation to each other. Progressive binding of trypsin by α2M was closely correlated with the loss of the methylamine-reactive sites in α2M: for each trypsin molecule bound, two such sites were inactivated. The results further showed that, even at low proteinase/α2M ratios, no unaccounted loss of trypsin-binding capacity occurred. As α2M is bivalent for trypsin binding and no trypsin bound to electrophoretic slow-form α2M was observed, this indicates that the two sites must react (bind trypsin) in rapid succession. Reaction of [14C]methylamine with α2M was biphasic in time; in the initial rapid phase complex-formation with trypsin caused a largely increased incorporation of methylamine. In the subsequent slow phase trypsin had no such effect. These results prompted further studies on the kinetics of methylamine inactivation of α2M with time of methylamine treatment. It was found that conformational change of α2M and decrease in trypsin binding (activity resistant to soya-bean trypsin inhibitor) showed different kinetics. The latter decreased rapidly, following pseudo-first-order kinetics. Conformational change was much slower and followed complex kinetics. On the other hand, binding of 125I-labelled trypsin to α2M did follow the same kinetics as the conformational change. This discrepancy between total binding (125I radioactivity) and trypsin-inhibitor-resistant binding of trypsin indicated formation of anomalous complexes, in which trypsin could still be inhibited by soya-bean trypsin inhibitor. Further examination confirmed that these complexes were proteolytically active towards haemoglobin and bound 125I-labelled soya-bean trypsin inhibitor to the active site of trypsin. The inhibition by soya-bean trypsin inhibitor was slowed down as compared with reaction with free trypsin. The results are discussed in relation to the subunit structure of α2M and to the mechanism of formation of the complex.

scholarly journals Relation of internal thioesters to conformational change and receptor-recognition site in α2-macroglobulin complexes

1982 ◽  
Vol 203 (2) ◽  
pp. 405-411 ◽  
Author(s):  
F Van Leuven ◽  
P Marynen ◽  
J J Cassiman ◽  
H Van den Berghe
Keyword(s):  
Monoclonal Antibody ◽  
Conformational Change ◽  
Trypsin Inhibitor ◽  
Soya Bean ◽  
Recognition Site ◽  
Thiol Groups ◽  
Α2 Macroglobulin ◽  
Receptor Recognition ◽  
Complex Receptor ◽  
Bean Trypsin Inhibitor

The unique steric type of inhibition of endopeptidases by human alpha 2-macroglobulin (alpha 2-M) and the inactivation of the latter by methylamine were examined in relation to the internal thioesters in alpha 2M. The present results confirm our previous findings that disruption of the internal thioesters, is not in itself sufficient to cause the conformational change of alpha 2M typical of alpha 2-M-proteinase complexes; the electrophoretically slow form of alpha 2M with [14C]methylamine incorporated was isolated. Moreover, this group is stabilized by derivatization of the exposed cysteine thiol groups. Cyanylation with 2,4-dinitrophenyl thiocyanate during the methylamine reaction was the most effective procedure, yielding essentially only slow-form alpha 2M. Other thiol-specific reagents were less effective. When allowed to react with trypsin the cyanylated derivative (slow-form alpha 2M with thioesters broken) produced anomalous complexes; only half the expected amount of trypsin was bound, whereas the complexes were fully inhibited by soya-bean trypsin inhibitor and were proteolytically active. Despite this, the anomalous complexes were recognized by two highly specific probes: the fibroblast alpha 2M-complex receptor and the monoclonal antibody (F2B2) directed against the receptor-recognition site on alpha 2M complexes. The results show that the internal thioesters in alpha 2M are necessary for the conformational change producing sterically inhibited endoproteinase complexes, but do not participate as such in receptor-mediated endocytosis of these complexes.

Activation of latent collagenase from polymorphonuclear leukocytes by cathepsin G

1979 ◽  
Vol 44 (10) ◽  
pp. 3177-3182 ◽  
Author(s):  
Mária Stančíková ◽  
Karel Trnavský
Keyword(s):  
Affinity Chromatography ◽  
Trypsin Inhibitor ◽  
Polymorphonuclear Leukocytes ◽  
Soya Bean ◽  
Cathepsin G ◽  
Sepharose Column ◽  
Bean Trypsin Inhibitor ◽  
Human Polymorphonuclear Leukocytes

Cathepsin G was isolated from human polymorphonuclear leukocytes and purified by affinity chromatography on Antilysin-Sepharose column. Purified enzyme activated later collagenase isolated from leukocytes. Activation at 36°C was maximal after 30 min incubation. Inhibitors of cathepsin G - soya-bean trypsin inhibitor, diisopropyl phosphofluoridate and Antilysin were active in inhibiting the activation of latent collagenase by cathepsin G.

scholarly journals Raw soya-bean flour increases cholecystokinin release in man

1987 ◽  
Vol 58 (2) ◽  
pp. 175-179 ◽  
Author(s):  
John Calam ◽  
Joanna C. Bojarski ◽  
Caroline J. Springer
Keyword(s):  
Heat Treatment ◽  
Trypsin Inhibitor ◽  
Soya Bean ◽  
The Other ◽  
Oral Ingestion ◽  
Pancreatic Acini ◽  
Bean Flour ◽  
Heat Treated ◽  
Releasing Effect ◽  
Cck Release

1. The aim of the present study was to determine whether oral ingestion of raw soya-bean flour, which contains trypsin inhibitors, alters the release of cholecystokinin (CCK) in man.2. Eleven healthy volunteers ate two mixed meals: one with raw soya-bean flour and the other with soya-bean flour that had been heat-treated. The two flours inhibited 34 and 3 mg trypsin/g flour respectively.3. CCK was measured in plasma using a bioassay based on the release of amylase (EC 3.2.1.1) from dispersed rat pancreatic acini.4. The peak CCK response was 168 (SE 8.1) pmol/l with raw soya-bean flour but 4.9 (SE 2.8) pmol/l with heat-treated flour (P < 0.05).5. We conclude that ingestion of raw soya-bean flour increases CCK release in man and that heat treatment which reduces the trypsin inhibitor content of the flour also diminishes its CCK-releasing effect.

scholarly journals Proteinase inhibitors in rat serum. Purification and partial characterization of three functionally distinct trypsin inhibitors

1984 ◽  
Vol 218 (3) ◽  
pp. 953-959 ◽  
Author(s):  
L Kuehn ◽  
M Rutschmann ◽  
B Dahlmann ◽  
H Reinauer
Keyword(s):  
Proteinase Inhibitor ◽  
Proteinase Inhibitors ◽  
Serine Proteinase ◽  
The Other ◽  
Serine Proteinases ◽  
Rat Serum ◽  
Apparent Homogeneity ◽  
Human Counterpart ◽  
Proteinase Inhibitor Ii

Three different serine proteinase inhibitors were isolated from rat serum and purified to apparent homogeneity. One of the inhibitors appears to be homologous to alpha 1-proteinase inhibitor isolated from man and other species, but the other two, designated rat proteinase inhibitor I and rat proteinase inhibitor II, seem to have no human counterpart. alpha 1-Proteinase inhibitor (Mr 55000) inhibits trypsin, chymotrypsin and elastase, the three serine proteinases tested. Rat proteinase inhibitor I (Mr 66000) is active towards trypsin and chymotrypsin, but is inactive towards elastase. Rat proteinase inhibitor II (Mr 65000) is an effective inhibitor of trypsin only. Their contributions to the trypsin-inhibitory capacity of rat serum are about 68, 14 and 18% for alpha 1-proteinase inhibitor, rat proteinase inhibitor I and rat proteinase inhibitor II respectively.

scholarly journals Surface-simulation synthesis of the substrate-binding site of an enzyme. Demonstration with trypsin

1985 ◽  
Vol 226 (2) ◽  
pp. 477-485 ◽  
Author(s):  
M Z Atassi
Keyword(s):  
Binding Site ◽  
Trypsin Inhibitor ◽  
Binding Activity ◽  
Enzymic Activity ◽  
Soya Bean ◽  
Free Form ◽  
Protein Substrates ◽  
Substrate Analogues ◽  
Bean Trypsin Inhibitor ◽  
Alpha 1 Antitrypsin

From the X-ray co-ordinates of bovine trypsin and its complexes with substrate analogues (benzamidine) and with soya-bean trypsin inhibitor, a peptide (TP) was designed and synthesized by surface-simulation synthesis, a concept previously introduced by this laboratory, to mimic the binding site of trypsin. Also, a control peptide (CTP) was synthesized that contained all the amino acids present in the TP peptide, except that their order was randomized. The radioiodinated TP peptide bound specifically to adsorbents of benzamidine, whereas the control CTP peptide exhibited no binding activity. Conjugates to succinyl (3-carboxypropionyl)-lysozyme of the TP peptide, control CTP peptide and other unrelated peptides were examined by a radiometric binding assay for the ability to bind soya-bean trypsin inhibitor and human alpha 1-antitrypsin. Conjugates of the TP peptide exhibited considerable binding activity to adsorbents of soya-bean trypsin inhibitor or alpha 1-antitrypsin. None of the other peptide conjugates possessed any binding activity. Action of the active-site-directed reagents phenylmethanesulphonyl fluoride and di-isopropyl phosphorofluoridate on free TP and CTP peptides resulted in the modification of a serine residue in the TP peptide whereas the CTP peptide remained unaltered. The TP peptide, either in the free form or as a conjugate on succinyl-lysozyme, had no enzymic activity on protein substrates or on tosylarginine methyl ester. These findings indicated that the binding activity of an enzyme was well mimicked by the surface-stimulation peptide but that reproduction of the catalytic activity was not obtained.

An Endogenous Protease Activating Plasma Inactive Renin

1978 ◽  
Vol 55 (s4) ◽  
pp. 133s-134s ◽  
Author(s):  
B. J. Leckie
Keyword(s):  
Human Plasma ◽  
Serine Protease ◽  
Protease Inhibitors ◽  
Trypsin Inhibitor ◽  
Soya Bean ◽  
Acid Activation ◽  
Bean Trypsin Inhibitor ◽  
Inactive Renin ◽  
Inhibited Acid ◽  
Endogenous Protease

1. The protease inhibitors Trasylol and soya-bean trypsin inhibitor prevented the activation of plasma inactive renin by acid. 2. N-Ethylmaleimide inhibited acid-activation to some extent but o-phenanthroline had no effect. 3. Acid-activation of the inactive renin in human plasma is mediated by a serine protease.

scholarly journals EFFECT OF BLOOD THROMBOKINASE, AS INFLUENCED BY SOY BEAN TRYPSIN INHIBITOR; ULTRACENTRIFUGATION, AND ACCESSORY FACTORS

1955 ◽  
Vol 38 (6) ◽  
pp. 757-769 ◽  
Author(s):  
J. H. Milstone
Keyword(s):  
Trypsin Inhibitor ◽  
Calcium Ions ◽  
Barium Carbonate ◽  
The Other ◽  
Potential Source ◽  
Accessory Factor ◽  
Bean Trypsin Inhibitor ◽  
Ionic Calcium ◽  
Accessory Factors ◽  
Almost All

1. Crystallized soy bean trypsin inhibitor, at a concentration of 100 µg./ml., suppressed the production of thrombin from a mixture of prothrombin and blood thrombokinase. The experiment was performed in the presence of 0.011 M oxalate, in order to minimize the possibility of participation by accessory factors which require ionic calcium. The results are in accord with the view that thrombokinase is a trypsin-like enzyme. 2. When a solution of blood thrombokinase was centrifuged at 85,000 g for 120 minutes, almost all the activity remained in the supernate. This supernate activated the supernate from a prothrombin solution which had been similarly centrifuged. The activation of prothrombin by thrombokinase can proceed in the absence of material completely sedimentable in 120 minutes at 85,000 g. 3. An "accelerator" reagent was prepared by treating bovine serum with barium carbonate, and then passing the serum through a column of diatomaceous earth. This "accelerator" was used together with prothrombin, blood thrombokinase, Howell's cephalin, and calcium chloride to compose a five-reagent thrombin-producing system. In this system, no thrombin was produced without thrombokinase. On the other hand, thrombin was produced from prothrombin and thrombokinase, even when all the other reagents were omitted. When calcium was omitted, thrombokinase was able to function; but cephalin and the "accelerator" reagent were ineffective. 4. Quantitative tests indicated that the "accelerator" reagent exerted an effect distinct from those of thrombokinase and cephalin. However, it is not certain whether the "accelerator" reagent functioned as an accessory factor, as a potential source of more thrombokinase, or both. In the experiments reported, thrombokinase was primary to, or necessary for, the effect of "accelerator." 5. The effectiveness of thrombokinase was multiplied a hundred times or more, when complemented by calcium, cephalin, and "accelerator" reagent. Ionic calcium was a necessary component of this complementing system. This may help to explain why removal of calcium ions keeps blood fluid, even though thrombokinase, by itself, is little influenced either by calcium ions or by oxalate.

Measurement of Endotoxin Levels in Plasma Using Limulus Amoebocyte Lysate and Chromogenic Substrate, S2222

1979 ◽  
Author(s):  
S Clark ◽  
M Scully ◽  
P Webb ◽  
V Kakkar
Keyword(s):  
Trypsin Inhibitor ◽  
Final Concentration ◽  
Soya Bean ◽  
Lag Phase ◽  
Chromogenic Substrate ◽  
Plasma Samples ◽  
Linear Calibration ◽  
Limulus Amoebocyte Lysate ◽  
Bean Trypsin Inhibitor ◽  
Pancreatic Trypsin Inhibitor

A method has been devised for the measurement of endotoxin in plasma using the chromogenic substrate, S2222, a substrate which has been shown to be particularly sensitive to the Limulus Lysate. Time curves of the rate of release of the chromogen in mixtures in which procoagulase activation was concurrent, were complex with a lag phase which was shortened by increasing endotoxin concentrations. At a final concentration of 0.5ng/ml and 370 activation was complete within 60 minutes. The enzyme was inhibited by soya bean trypsin inhibitor but not by pancreatic trypsin inhibitor or hirudin. In the method finally adopted the lysate (25µl) was incubated with endotoxin (E.coli 026.86 Difco) and magnesium chloride (final concentration 33mM) in a total volume of 225µl. After 12 minutes preincubation 165µl of S2222(0.4mM) was added and the increase in abdorbance at 405nm over two minutes measured using an Abbott Biochromatic Analyser 100. Linear assay curves were obtained with final concentration of 0.2 to 2.0ngs endotoxin/ml with ΔOD 405/min of 0.35 at 2.0ng endotoxin/ml of final incubation mixture. ΔOD /min in control tubes were of the order of 0.02. For measurement from plasma samples, endotoxin was first extracted with chloroform. Linear calibration curves were achieved at a concentration of endotoxin of 1 to 5ng/ml of whole blood with a net OD/min at the highest concentration of 0.25.

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