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H Fritz

Publications and source records attributed to H Fritz.

At least 181 records · Page 10Linked to original sources
PubMed1983

Structural aspects of human kininogens.

Kininogens have been purified from human plasma to apparent homogeneity. Native human LMW kininogen is a single-chain (glyco-) protein of molecular weight 68,000, which is converted to a two-chain protein by limited proteolysis with tissue kallikrein to form a heavy chain (Mr 62,000) and a light chain (Mr 4,000). Human HMW kininogen represents a single chain (glyco-)protein of Mr 114,000 which is split into two chains of similar size (H-chain of Mr 58,000 and L-chain of Mr 62,000) by limited proteolysis with tissue kallikrein. Sequence analysis of the isolated L-chain of human MW kininogen indicates a partial homology to the corresponding fragment-1.2 of bovine HMW kininogen. Purified kininogens readily form self-aggregates ranging from dimer to hexamer (HMW kininogen) and from dimer to decamer (LMW kininogen), respectively. Self-association is completely reversible in the presence of dissociating agents. Preliminary evidence suggests that oligomerisation is mediated by the H-chain common to the two types of kininogens.

Amino Acid Sequence↗
PubMed1982

Factors determining steric course of enzymic glycosylation reactions: glycosyl transfer products formed from 2,6-anhydro-1-deoxy-D-gluco-hept-1-enitol by alpha-glucosidases and an inverting exo-alpha-glucanase.

Glycosyl transfer products were formed from 2,6-anhydro-1-deoxy-D-gluco-hept-1-enitol (heptenitol) by purified alpha-glucosidases from Candida tropicalis and rice and by an inverting exo-alpha-glucanase (glucodextranase) from Arthrobacter globiformis. The products were structurally defined through 1H and 13C NMR (nuclear magnetic resonance) spectra of their crystalline per-O-acetates in comparison with those of authentic methyl 1-deoxy-alpha- and methyl 1-deoxy-beta-D-gluco-heptuloside. 1-Deoxy-alpha-D-gluco-heptulosyl-(2 leads to 7)-heptenitol and 1-deoxy-alpha-D-gluco-heptulosyl-(2 leads to 7)-D-gluco-heptulose were produced by both the Candida alpha-glucosidase and the glucodextranase; 1-deoxy-alpha-D-gluco-heptulosyl-(2 leads to 5)- and 1-deoxy-alpha-D-gluco-heptulosyl-(2 leads to 7)-D-gluco-heptuloses by the rice alpha-glucosidase. These results, together with our earlier findings of sterospecific hydration of heptenitol catalyzed by the same enzymes [Hehre, E. J., Brewer, C. F., Uchiyama, T., Schlesselmann, P., & Lehmann, J. (1980) Biochemistry 19, 3557-3564], show the inadequacy of the long-accepted notion that carbohydrase-catalyzed reactions always lead to retention (or always lead to inversion) of substrate configuration. In particular, the finding that glucodextranase forms transfer products of alpha configuration and a hydration product of beta configuration from the same substrate provides a clear example of the functioning of acceptors rather than donor substrates in selecting the steric course of reactions catalyzed by a glycosylase. The circumstances under which acceptor cosubstrates might be expected to show this significant effect are discussed. The opportunity presumably would exist whenever carbonium ion mediated reactions are catalyzed by glycosylases that provide oppositely oriented approaches of different acceptors to the catalytic center.

Arthrobacter↗
PubMed1982

Acid extraction of acrosin from human spermatozoa pretreated by different physicochemical methods.

Washed human spermatozoa were subjected to different physicochemical methods, followed by acid extraction of the sperm acrosomes to dissolve acrosin. The acrosin activity of the sperm pellet and the supernatant was determined by benzoyl arginine ethyl ester/alcohol dehydrogenase (BAEE/ADH) assay to calculate the total acrosin activity in mU/10(6) spermatozoa. Membrane-active and zymogen-activating agents increased the total acrosin activity 50%-200% compared to acid extraction alone. Similar results were obtained by osmotic shock, sonication and treatment with glass beads. Snap freezing of unprotected spermatozoa in liquid nitrogen yielded a fivefold increase in total acrosin activity, thus demonstrating that this is the method of choice for optimal acrosin extraction. The possibility is discussed as to whether acrosomal membrane alterations with improved solubilization of membrane-bound acrosin and/or conformational changes and/or zymogen activation are responsible for the considerable increase observed in acrosin activity.

Acids↗
PubMed1982

Disturbances of selected plasma proteins in hyperdynamic septic shock.

This study was performed on patients (n = 18) suffering from strictly defined hyperdynamic septic shock. Plasma factors (C-reactive protein, acid alpha 1-glycoprotein, fibrinogen, fibrinopeptide A, fibrinogen-fibrin split products, factor XIII, antithrombin III, complement factors C3 and C4, inter-alpha-trypsin-inhibitor and alpha 2-macroglobulin) measured during hyperdynamic septic shock were highly abnormal. The activation and consumption of clotting, fibrinolytic and complement factors due to system-specific proteinases (such as thrombokinase or plasminogen activators) seemed to be intensified by the nonspecific proteolytic activity of granulocytic proteinases probably released by the action of endotoxins. Possible therapeutic measures to maintain the endogeneous defence mechanism against enhanced proteolysis during septic shock are discussed.

Alpha-Globulins↗
PubMed1982

A new acrosin inhibitor from boar spermatozoa.

A new proteinase inhibitor (Mr 7500) was isolated to apparent homogeneity from boar spermatozoa by repeated gel filtration on Sephadex G-50 and affinity chromatography on concanavalin-A--Sepharose 4B. The inhibitor strongly inhibits boar acrosin in a competitive 1:1 stoichiometric reaction with Kass = 7 x 10(10)1 mol-1. The inhibitor is a glycoprotein and represents a first member of a new class of proteinase inhibitor with a rather short polypeptide backbone of only 42 amino acid residues and a low cystine content. The basic protein (isoelectric point 9.4) contains a single disulfide loop, which is easily reducible by sodium borohydride. Upon reduction the inhibitory activity is lost, but rapidly regained after air reoxidation of the corresponding half-cystine residues. The reactive site residue was established to be arginine by inhibition with 2,3-butanedione. The inhibitor is rather specific for acrosin and inhibits bovine trypsin only to a limited extent. However, incubation with catalytic amounts of trypsin (or acrosin) at acid pH (pH2-3) rapidly leads to a limited proteolysis at the reactive site with formation of 67% modified (reactive site hydrolysed), but still active inhibitor. The equilibrium constant was established to be Khyd = 2.0.

Acrosin↗
PubMed1982

Determination of bradykinin, kallidin and Met-Lys-bradykinin by high performance liquid chromatography.

A high performance liquid chromatography system was developed for the quantitative separation and determination of bradykinin, kallidin and Met-Lys-bradykinin using a reversed-phase column (Nucleosil 5 C8) and an isocratic buffer system. The lower limit of detection is 20 pmol for bradykinin. The intra-variation coefficient of the assay is between 1.8 and 5.7%. The recovery of bradykinin is higher than 96%. Addition of human serum albumin to the assay system in a concentration of 40% lead to a remarkable reduction of the detectable kinin level, which indicates an adsorption of kinins to serum albumin.

Amino Acid Sequence↗
PubMed1981

Sperm Acrosin.

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Acrosin↗
PubMed1981

Inhibitors of acrosomal proteinase as antifertility agents. A problem of acrosomal membrane permeability.

In vitro studies were performed to investigate the accessibility of acrosin to various proteinase inhibitors inside the intact acrosome of testicular, ejaculated, and uterine human spermatozoa. As test system the gelatin plate assay was used. For this assay it was shown formerly that a correlation exists between the size of the digested lysis areas (halo formation) and acrosin activity estimated with synthetic substrates. In addition, saturation of the gelatin substrate membranes with acrosin inhibitors including highly specific ones before application of spermatozoa completely prevented halo formation indicating that the gelatinolytic activity of human spermatozoa is caused exclusively by acrosin. When human spermatozoa were incubated with various acrosin inhibitors (concentration: 1 mmol/l) prior to application to the gelatin membrane, reduction of halo formation could not be observed, however. This result indicates that most of the tested acrosin inhibitors (9 naturally occurring protein inhibitors, 2 microbial peptide inhibitors, 19 synthetic inhibitors) were unable to penetrate the acrosomal membranes of testicular, ejaculated, and uterine human spermatozoa. Only 2 inhibitors caused moderate up to complete inhibition of the gelatinolytic activity of the spermatozoa if applied in concentrations between 1 and 10 mmol/l: the proteinase inhibitor aprotinin and the synthetic inhibitor NPGB (4-nitrophenyl 4-guanidinobenzoate). Obviously, human acrosomal membranes seem to be especially impenetrable to proteins, polypeptides, and synthetic agents. Those acrosin inhibitors penetrating the human sperm head membranes are either too toxic or the local concentration necessary for effective acrosin inhibition in vivo cannot be achieved within the male or female genital tract secretions. Therefore, acrosin inhibitors cannot be used for human contraception at present. Thus it is mandatory to continue the search for suitable acrosin inhibitors with low toxicity easily penetrating into the intact sperm acrosome.

Acrosome↗
PubMed1981

Clotting and other plasma factors in experimental endotoxemia: inhibition of degradation by exogenous proteinase inhibitors.

Endotoxemia in dogs was induced by a slow intravenous infusion of E. coli endotoxin for 2 h. Thereby, a significant decrease was observed in the plasma levels of several clotting, fibrinolysis and complement factors. The changes were studied over an experimental period of 14 h and checked for statistical significance by three-way analysis of variance. Application of the broad-spectrum proteinase inhibitor aprotinin (Trasylol) from bovine organs clearly lowered the endotoxin-induced decline of the plasma proteins studied. By intravenous application of a specific granulocytic proteinase inhibitor (Bowman-Birk inhibitor from soybeans), the endotoxin-induced reduction of the plasma proteins was prevented in a similar manner. It can be concluded that at least some of the pathobiochemical mechanisms observed in clotting, fibrinolysis and complement systems during endotoxemia are not only caused by a severe consumption reaction but also by unspecific proteolytic degradation due to neutral granulocytic proteinases.

Animals↗
PubMed1981

Effect of human granulocytic elastase on isolated human antithrombin III.

The interaction of elastase isolated from human granulocytes with purified human antithrombin III was investigated. Antithrombin III did not display any inhibitory effect on granulocytic elastase. Dependent on enzyme concentration, however, granulocytic elastase induced progressive inactivation of antithrombin III leading to an almost complete loss of the thrombin inhibitory activity at a molar ratio of elastase: antithrombin III = 0.4:1 within 5 min at 25 degrees C. Antithrombin III is not drastically degraded by elastase as revealed by polyacrylamide gel electrophoretic and rocket immunoelectrophoretic investigations. However, characterization by two-dimensional immunoelectrophoresis with heparin in the first dimensional gel layer revealed a distinct change in the electrophoretic mobility of the inhibitor preincubated with elastase compared to native antithrombin III. This indicates that heparin binding sites of antithrombin III are occupied or affected by the elastase-induced peptide bond cleavage(s). Granulocytic proteinase inhibitors (eglin, Bowman-Birk inhibitor) proved to be highly effective in preventing the antithrombin III inactivation by degradation due to elastase. It is assumed that at least part of the antithrombin III consumption in diseases such as septicemia or endotoxemia is due to proteolysis by granulocytic proteinases. Application of specific inhibitors in the early phase of these ailments should be able to prevent this unspecific degradation of the endogenous antithrombin III.

Antithrombin III↗
PubMed1981

Progressive inhibition of human glandular (urinary) kallikrein by human serum and identification of the progressive antikallikrein as alpha 1-antitrypsin (alpha 1-protease inhibitor).

Human urinary kallikrein was inhibited by human alpha 1-antitrypsin (alpha 1-protease inhibitor) in a similar way as by equivalent amounts of human serum. The inhibitor present in the kallikrein-inhibitor complex formed was identified as alpha 1-antitrypsin by two-dimensional immunoelectrophoresis. Under the experimental conditions applied, 90 mIU (= 185 microgram) alpha 1-antitrypsin inhibits about 9 microgram of human urinary kallikrein in 24 h at 37 degrees C, 1 ml of human serum, containing 2-4 mg alpha 1-antitrypsin, inhibits about 70 microgram kallikrein. At an incubation temperature of 25 degrees C, the rate of inactivation is significantly lower than at 37 degrees C. No inhibition was observed at 0 degrees C or when alpha 1-antitrypsin was presaturated with trypsin.

Humans↗
PubMed1981

A convenient large-scale preparation of high molecular weight kininogen from human plasma.

Human high molecular weight (HMW) kininogen was purified by chromatography on DEAE-Sephadex A-50 and CM-Sephadex C-50, followed by gel filtration on Sephadex G-50. From 5 l fresh human plasma approximately 120 mg HMW kininogen was obtained. The yield was 40%. The preparation had a specific activity of 14 microgram bradykinin equivalent/A280 unit. Upon polyacrylamide disc gel electrophoresis HMW kininogen was separated into two close bands, whereas only one band with an apparent Mr of 120 000 was obtained in sodium dodecyl sulfate electrophoresis. Both protein fractions separated in disc gel electrophoresis released kinins upon incubation with kallikreins. The purified HMW kininogen had an isoelectric point of 4.65 when measured by isoelectric focusing. The amino acid composition of the purified HMW kininogen is given. The amino terminus of the molecule is blocked. In oligomerization studies adducts with molecular weights up to 810 000 were obtained. HMW kininogen gave a single precipitin arc in immunoelectrophoresis with antiserum directed against HMW kininogen.

Amino Acids↗
PubMed1981

The suitability of carboxymethylcellulose as a vehicle in reproductive studies.

The 2% aqueous solution of a sodium carboxymethylcellulose (CMC) was administered by gavage to 20 male and 40 female albino rats at the daily volume of 1 ml/100 g body weight. The males were treated for at least 60 days and the females for at least 14 days prior to mating and during a 6-day mating period. In one half of the females treatment was continued until sacrifice on day 14 of pregnancy; in the other half of the female treatment was continued until weaning of the progeny. A variety of tests was used to examine the behavioural performance of the pups. The overall results of this study were comparable for both test groups, CMC treated and untreated. Consequently, the CMC used here is considered to be a suitable vehicle for suspending tests materials for oral administration in long-term reproductive studies in rats.

Animals↗