PubMed Health⌕ Search

Biomedical subjects

U Seemüller

Publications and source records attributed to U Seemüller.

15 recordsLinked to original sources
PubMed1987

Influence of chain shortening on the inhibitor properties of hirudin and eglin c.

To find out minimal sizes of the proteinase inhibitor proteins hirudin and eglin necessary for their biological activity the inhibitors were incubated with exopeptidases. From the incubation mixtures shortened derivatives were isolated and characterized. Eglin c can be N-terminally shortened by up to 6 amino-acid residues without any loss of affinity towards chymotrypsin. The complex of thrombin with hirudin lacking 3 C-terminal amino-acid residues showed a 15-20-fold increased Ki value as found previously for desulfato-hirudin and desulfato-hirudin shortened by 2 amino-acid residues. Obviously, the C-terminal part of the hirudin molecule has a positive influence on its affinity to thrombin.

Amino Acids↗
PubMed1986

Molecular cloning and expression of cDNA for human antileukoprotease from cervix uterus.

We have isolated cDNA clones for the human antileukoprotease HUSI-I, an elastase inhibitor, from a library, containing cDNA inserts made from human cervix uterus. A library of 10 000 recombinants was screened using a mixture of 16 different oligodeoxyribonucleotides which correspond to amino acids 79-84 and one 20mer oligodeoxyribonucleotide corresponding to amino acids 19-26. Two overlapping cDNA clones, containing the entire coding sequence and part of the 5'- and 3'-untranslated region, were isolated. DNA sequence data showed that our clone corresponds with the available protein sequence data. For expression, the cDNA fragment was inserted in a derivative of plasmid pPLc236 and expressed under the control of lambda PL promoter. Expression of antileukoprotease was proven by Western blot analysis and inhibition of chymotrypsin.

Amino Acid Sequence↗
PubMed1986

The acid-stable proteinase inhibitor of human mucous secretions (HUSI-I, antileukoprotease). Complete amino acid sequence as revealed by protein and cDNA sequencing and structural homology to whey proteins and Red Sea turtle proteinase inhibitor.

The complete amino acid sequence of human antileukoprotease has been determined by direct sequencing of the inhibitory active protein isolated from seminal plasma (HUSI-I) and by sequence analysis of cDNA reverse-transcribed from mRNA prepared from cervical tissue. The inhibitor (Mr 11726) consists of 107 amino acid residues including 16 cysteines presumably forming disulfide bonds. The molecule comprises two consecutive domains which are homologous to each other, to the second domain of the basic protease inhibitor from Red Sea turtle (chelonianin) and to both domains of the whey proteins of rat and mouse. Both domains contain a pattern of cysteines known as the 'four-disulfide-core' that has also been found in wheat germ agglutinin and neurophysin.

Amino Acid Sequence↗
PubMed1986

Isolation and characterization of hirudin isoinhibitors and sequence analysis of hirudin PA.

A five-step isolation procedure has been developed for the purification of isoforms of hirudin (isohirudins) from whole leeches. The final purification of two thrombin-inhibiting preparations by reversed-phase high-performance liquid chromatography yielded several isohirudins with either N-terminal valine or isoleucine but with identical inhibition characteristics, i.e. specific thrombin inhibiting activities of 680-720 IU/mg and dissociation constants Ki of the thrombin-inhibitor complexes close to 3 X 10(-11) mol/l. The inhibitor with N-terminal isoleucine was designated hirudin PA. This inhibitor contains 66 amino-acid residues and has a molecular mass of 7,087 Da. The complete amino-acid sequence of hirudin PA was established by automated solid-phase Edman degradation of the native and oxidized inhibitor and two of its tryptic fragments. On the basis of the primary structures two types of thrombin inhibitors from the leech can be distinguished, designated hirudin and hirudin PA. The degree of structural homology of both isoinhibitors is approximately 82%; both have a tyrosine-O-sulfate residue near the C-terminus.

Amino Acid Sequence↗
PubMed1985

Elastase-cathepsin G inhibitors eglin b and eglin c differ by a single Tyr----His substitution. A micro-method for the identification of amino-acid substitution.

The structures of eglin b and eglin c, both potent inhibitors of human neutral granulocytic proteinase elastase and cathepsin G, were compared by micro amino-acid analysis and peptide mapping techniques. Eglin b and eglin c differ by one amino-acid substitution in the middle of the polypeptide chain. Tyrosine residue at position 35 of eglin c was substituted by histidine in eglin b. This amino-acid substitution requires one base exchange (U----C) at the DNA level and apparently does not affect the reactive site of eglins. Though without disulfide linkages, eglins are very rigid molecules and can be effectively digested by trypsin only after rigorous acid incubation.

Amino Acids↗
PubMed1985

The complete covalent structure of hirudin. Localization of the disulfide bonds.

Hirudin, the thrombin-specific inhibitor from the leech Hirudo medicinalis, is a single-chain polypeptide (65 amino-acid residues) linked by three disulfide bridges. Localization of the three disulfide bonds could be assigned on the basis of the structures of cystine peptides derived by high performance liquid chromatography separations of thermolysinolytic digest of native hirudin. By characterization of the nine major fragments by amino-acid analysis, N-terminal amino-acid determination and sequence analysis, the following disulfide linkages were identified: Cys6-Cys14, Cys16-Cys28 and Cys22-Cys39. Due to the lack of any closer sequence homology and topological structural homology to other serine proteinase inhibitor proteins, hirudin seems to be unique in its primary structure and hence designates an unknown inhibitor family.

Amino Acid Sequence↗
PubMed1985

Eglin c, a pharmacologically active elastase inhibitor.

Eglin c is an elastase/cathepsin G inhibitor from leech Hirudo medicinalis. The gene for this 70 aminoacid peptide was synthesized chemically, cloned and expressed by E. coli. Here we report biochemical and pharmacological studies. The rate of complex formation between Eglin c and human leukocyte elastase (HLE) or human cathepsin G (H. Cat. G) was determined and compared to those of a number of other proteinase/proteinase-inhibitor interactions (alpha 1 PI and alpha 2M). The association rate constants of Eglin c with the leukocyte enzymes are of the same order of magnitude as those with the naturally occurring inhibitors alpha 1 PI and alpha 2M. The association rate constant of Eglin c (extracted from leech) and Eglin c (biotechnology product) with HLE was found to be identical. The equilibrium constants Ki of the Eglin c/HLE and the Eglin c/H. Cat. G interactions are in the order of 10(-10) M. In an experiment with the hamster emphysema model, 0.5 mg or 2 mg of Eglin c applied intratracheally one hour before an HLE-insult completely protected the animals against emphysema and no signs of toxicity due to Eglin c were observed.

Animals↗
PubMed1985

Inhibition of horse leucocyte proteinases by eglin, a proteinase inhibitor from leeches.

Interaction of eglin c with three neutral proteinases (1, 2A and 2B) from horse leucocytes was investigated using synthetic and protein substrates. With N-tert-butyloxycarbonyl-L-alanine-p-nitrophenyl ester as substrate inhibition of proteinase 1 and 2A was practically complete at equimolar inhibitor concentrations (Ki below 1 nMol/l). The complex with proteinase 2B showed a dissociation constant of approximately 25 nMol/l. The latter proteinase was only partly inhibited also in the presence of azocasein, whereas almost linear inhibition was observed for all 3 proteinases with fibrinogen as substrate. The inhibition rate constants (kon) for horse leucocyte proteinases with eglin were in the range of 8 to 13 X 10(5) M-1 S-1.

Animals↗
PubMed1984

Kinetics of the inhibition of human leucocyte elastase by eglin from the leech Hirudo medicinalis.

The rate constants for the inhibition of human leucocyte elastase by eglin from the leech Hirudo medicinalis were determined by using a pre-steady-state kinetic approach. kon and koff for complex-formation and dissociation were 1 X 10(6)M-1 X S-1 and 8 X 10(-4)S-1 respectively. Ki was calculated as the ratio koff/kon = 8 X 10(-10)M, the binding of eglin to elastase was reversible and the inhibition mechanism was of the fully competitive type. The mechanistic properties of the system and the biological significance of the rate constants are discussed.

Animals↗
PubMed1983

Sequence determination of eglin C using combined microtechniques of amino acid analysis, peptide isolation, and automatic Edman degradation.

The complete amino acid sequence of a proteinase inhibitor, eglin c (Mr 8100), has been determined with less than 150 micrograms of the protein using the following microtechniques: (a) amino acid analysis with a low-nanogram amount of protein hydrolysate using dimethylaminoazobenzene sulfonyl chloride, (b) peptide isolation at the picomole level using the dimethylaminoazobenzene isothiocyanate (DABITC) precolumn derivatization method, and (c) automatic Edman degradation. One amino acid residue has been corrected for the previously reported sequence. The Contribution of each technique to the microsequencing is discussed. In addition, a new high-performance liquid chromatography system that gives a complete baseline separation of all phenylthiohydantoin-amino acids is described.

Amino Acid Sequence↗
PubMed1980

[Enhanced enzymatic activity of Crohn's disease and ulcerative colitis (author's transl)].

1. An enhanced collagenolytic activity in the bowel tissue samples of M. Crohn and ulcerative colitis is demonstrated. 2. No inhibition of the collagenolytic activity was found when the specific collagenase inhibitor EDTA was applied. 2. In vitro, the application of EGLIN B resulted in a significant decrease of collagenolysis. EGLIN is a recently detected inhibitor of serine proteases such as Elastase.

Colitis, Ulcerative↗
PubMed1980

Structure of the elastase-cathepsin G inhibitor of the leech Hirudo medicinalis.

The leech Hirudo medicinalis contains three different groups of proteinase inhibitor proteins, the thrombin-specific hirudin, the bdellins directed against trypsin, plasmin and acrosin, and the eglins which were discovered only recently. We are interested in the eglins mainly for two reasons: (i) They form strong complexes with the granulocytic elastase and cathepsin G with Ki values close to 1 x 10(-10) mol/l. Due to this property they are potential candidates for the therapeutic treatment of various diseases. (ii) Although the eglins do not contain a disulfide bridge to stabilize the tertiary structure, they are highly resistant to denaturation by acidification and by heat as well as to proteolytic degradation.

Amino Acid Sequence↗
PubMed1977

Isolation and characterisation of a low molecular weight inhibitor (of chymotrypsin and human granulocytic elastase and cathepsin G) from leeches.

Two protein proteinase inhibitors were isolated and purified from the leech Hirudo medicinalis by means of gel filtration and ion-exchange chromatography. They inhibit chymotrypsin, subtilisin and the granulocytic neutral proteases elastase and cathepsin G. They proved to be homogeneous in polyacrylamide and dodecylsulfate gel electrophoresis and by end group analysis; only threonine was found as N-terminal amino acid residue using the dansylation technique. These inhibitors, which we call eglins, are stable in neutral and weakly acid (pH 3) solutions and resist non-specific proteolysis. From the amino acid compositions, a molecular weight of 6 600 - 6 800 is calculated for both inhibitory proteins, which is in good agreement with a value of about 6000 estimated by dodecylsulfate electrophoresis. The eglins contain an unusually large amount of hydrophobic amino acid residues but no methionine, isoleucine or--a rarity--cysteine residues or disulfide bridges. To our knowledge, the eglins are the first examples of proteinase inhibitors of the protein type which are not stabilized by disulfide bridges.

Amino Acids↗