Search PubMed⌕ Search

Biomedical subjects

C Kettner

Publications and source records attributed to C Kettner.

33 records · Page 2Linked to original sources
PubMed1981

The specificity of macrophage elastase on the insulin B-chain.

The specificity of macrophage elastase obtained from mouse peritoneal exudative macrophages was determined in the hydrolysis of the oxidized insulin B-chain. This elastase hydrolysed two bonds, namely Ala-Leu and Tyr-Leu. The rate of hydrolysis of the latter was two to three times greater than that of the former. The hexapeptide Glu-Ala-Leu-Tyr-Leu-Val, obtained by cleavage of the insulin B-chain, was not hydrolysed by macrophage elastase. When EDTA was present, proteolysis of the B-chain was not observed. The macrophage elastase is therefore different from the neutrophil elastase in specificity and mechanism.

Animals↗
PubMed1981

The specificity of cathepsin B.

Peptidyl chloromethyl ketones, largely derived from arginine, inactivate cathepsin B (beef spleen) at rates that vary 300 fold according to sequence, but the residue in the P1 position is not responsible for this variation since homoarginine or nitroarginine in this position provide inhibitors as good or better than those containing arginine. Peptidyl chloromethyl ketones containing hydrophobic residues such as phenylalanine or valine in the P2 and P3 position are the most effective inhibitors of the group. Cystamine (bis-aminoethyl disulfide) inactivates cathepsin B by formation of a mixed disulfide. Derivatives of cystamine containing phenylalanine, such as bis-N,N'-Phe-cystamine and bis-N,N'-Ala-Ala-Phe-cystamine are more effective and represent a new class of affinity labels for cathepsin B. Immobilized peptidyl cystamine derivatives can be used for the purification of cathepsin B by covalent affinity chromatography. Cathepsin B from beef spleen has a pronounced carboxydipeptidase action on glucagon as described for the human liver enzyme. This action can be conveniently followed by high pressure liquid chromatography.

Affinity Labels↗
PubMed1979

Thrombocytin, a serine protease from Bothrops atrox venom. 1. Purification and characterization of the enzyme.

Thrombocytin, a platelet-activating enzyme from Bothrops atrox venom, has been purified to homogeneity by precipitation with sodium salicylate and chromatography on heparin--agarose. Thrombocytin is a single-chain glycoprotein with a molecular weight of 36 000 which contains 5.6% carbohydrate. It causes platelet aggregation, release of platelet serotonin, and activation of factor XIII. The most sensitive substrate for the amidolytic activity of thrombocytin was Tos-Gly-Pro-Arg-p-nitroanilide hydrochloride. The activity of thrombocytin on this substrate and on platelets was inhibited by diisopropyl fluorophosphate (DFP), soybean trypsin inhibitor, and several arginine chloromethyl ketones. Active site titration with nitrophenyl guanidinobenzoate demonstrated that approximately 86% of the preparation was in the active form. These experiments demonstrate the presence of serine and histidine in the active site of thrombocytin and suggest that thrombocytin is a classical serine protease with a platelet-activating activity similar to thrombin.

Amidohydrolases↗
PubMed1979

The susceptibility of urokinase to affinity labeling by peptides of arginine chloromethyl ketone.

Pro-Gly-ArgCH2Cl, a reagent corresponding to the C-terminal sequence generated in plasminogen on activation by urokinase (EC 3.4.99.26) and probably by other plasminogen activators, was prepared. Pro-Gly-ArgCH2Cl was effective in the inactivation of urokinase at the 10(-6) M level (Ki 68 micrometers and k2 0.47 min-1). In contrast, only a slow inactivation was obtained by 10(-2) M N-tosyllysine chloromethyl ketone. Glu-Gly-ArgCH2Cl, N,N-dimethylaminonaphthalene-5-sulfonyl-Glu-Gly-ArgCH2Cl, and Ac-Gly-Gly-ArgCH2Cl were more reactive than Pro-Gly-ArgCH2Cl against urokinase by factors of 25, 6, and 3, respectively. The effectiveness of arginine chloromethyl ketones as affinity labels is highly dependent on binding in the S2 and S3 sites, thus sequence variations in the reagents exhibited differences in reactivity of up to four orders of magnitude. The most effective reagents had Gly in P2. Ac-Gly-Gly-ArgCH2Cl inactivates urokinase 50 times more rapidly than it does plasmin, thus providing a means of distinguishing the activity of plasmin from its activating protease whereas urokinase is almost inert to Ala-Phe-LysCH2Cl, a reagent which inactivates plasmin at the 10(-7) M level.

Affinity Labels↗
PubMed1979

Inactivation of the plasminogen activator from HeLa cells by peptides of arginine chloromethyl ketone.

The binding specificities of human urinary urokinase (EC 3.4.99.26) and HeLa cell plasminogen activator were studied using peptidyl chloromethyl ketone inhibitors. A 125I-labeled fibrin assay has been developed to yield kinetic information. Reagents of the sequence X-Gly-ArgCH2Cl were the most effective. The susceptibility of the HeLa cell plasminogen activator differed from that of urokinase in several respects indicating the utility of this type of inhibitor in distinguishing between proteases of this specificity.

Amino Acid Chloromethyl Ketones↗
PubMed1978

Synthesis of peptides of arginine chloromethyl ketone. Selective inactivation of human plasma kallikrein.

Synthetic procedures have been developed for the preparation of peptides of arginine chloromethyl ketone and applied in the preparation of affinity labels which correspond to the -Pro-Phe-Arg- C terminus of bradykinin, a physiological cleavage site of kallikrein in kininogen. Two such reagents, Ala-Phe-ArgCH2C1 and Pro-Phe-ArgCH2C1, proved to be highly effective as well as selective affinity labels for human plasma kallikrein. For example, Pro-Phe-ArgCH2C1 inactivates plasma kallikrein 50% in 24 min at a concentration of 2 x 10(-8)M, while other trypsin-like proteases are less susceptible in inactivation than kallikrein, differing by a factor of 48 for plasmin and factors of 10(2)-10(5) for factor Xa, thrombin, and urokinase. The affinity of human plasma kallikrein for Ala-Phe-ArgCH2C1 (Ki = 0.078 micron) is about 60 times that for Ala-Phe-LysCH2C1(Ki = 4.9 micron), whereas human plasmin exhibits about the same affinity for the former affinity label (Ki = 1.3 micron) as for the latter (Ki = 0.83 micron). The rate constants for the irreversible step of the affinity labeling reaction, k2, are similar for affinity labels tested with the individual proteases: 0.35 min-1 for plasma kallikrein and 0.18 min-1 for plasmin.

Affinity Labels↗
PubMed1978

Inactivation of boar acrosin by peptidyl-arginyl-chloromethanes. Comparison of the reactivity of acrosin, trypsin and thrombin.

A survey of the reactivity of 16 peptidyl-argininyl-chloromethanes with boar acrosin indicated that these compounds as a general group of reagents were highly effective in the inactivation of acrosin since at least half of the reagents tested rapidly inactivated this protease at a concentration of 0.10 micrometer or lower. For example, Dns-Glu-Gly-ArgCH2Cl inactivates acrosin by 50% in 1.8 min at a concentration of 75 nM, whereas in contrast, a 14000-fold higher concentration of Nalpha-tosyllysyl-chloromethane is required to obtain an equivalent rate of inactivation. A comparison of the reactivity of acrosin and trypsin with the peptides of arginyl-chloromethane containing different substituents in the P2 and P3 positions suggests that the secondary binding sites of these two proteases are very similar. Reagents with homoarginine, lysine and D-arginine in the P1 position have also been prepared and evaluated, but these were considerably less effective than the corresponding arginyl-chloromethanes in the inactivation of both acrosin and trypsin.

Acrosin↗
PubMed1976

[On the epidemiology of recurrent and chronic bronchopulmonary diseases-an examination of about 18000 children. 3. Investigation in the district of Merseburg (author's transl)].

In the district of Merseburg, characterized by a very high degree of air pollution, we have examined 4445 children of the following 4 age-groups 5.-6., 8.-9., 11.-12., and 14.-16. years of life. As a result we found 3,04% of them suffering from recurrent bronchitis, 0,34% from chronic bronchitis and 0,43% from bronchial asthma. The frequency of morbidity on recurrent and chronic bronchitis lowered with increasing age of the children. In asthma, however, this relation did not exist. There were no differences of the frequency of chronic or recurrent bronchitis between the two sexes, but boys suffered much more often from asthma than girls. In places with a high degree of air pollution the frequency of morbidity was significantly higher than in places with somewhat lower air pollution.

Adolescent↗
PubMedDate not supplied

Anticoagulant activity of a peptide boronic acid thrombin inhibitor by various routes of administration in rats.

The peptide boronic acid analog Ac-(D)Phe-Pro-boroArg-OH (I) is a potent and selective inhibitor of thrombin. The objective of this study was to determine whether I is active orally or when administered by alternative transmucosal routes. The measured effect was the time for clotting of plasma after initiation with thrombin. With this assay there was a narrow window from no measurable effect to the maximal effect, a clotting time greater than 300 seconds. Intravenous I at a 0.15 mg/kg dose in rats, a nasal 0.45 mg/kg dose, and 3 mg/kg doses administered orally, colonically, or rectally all produced maximal effects. Therefore, although bioavailability cannot be estimated, it is demonstrated that this peptide analog was absorbed by each of these routes.

Administration, Intranasal↗