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E Jaeger

Publications and source records attributed to E Jaeger.

At least 37 records · Page 2Linked to original sources
PubMed1992

Inhibition of HIV-1 protease by short peptides derived from the terminal segments of the protease.

The active HIV-1 protease is a homodimeric enzyme. A beta-sheet consisting of N- and C-terminal segments provides the main driving force for dimerization of the inactive protomers. Several short peptides with sequences derived from the N- and C-termini of the protease were tested for inhibition of protease activity and for inhibition of HIV-1 replication in lymphocytes. Medium inhibitory activity was found with each of the peptides in the enzyme test and no inhibition of the lymphocytes was found up to 200 micrograms/ml. The enzyme tests indicate that HIV-1 protease is the target of the inhibitory action. Synergistic action could not be found with pairs of the peptides derived from the two different termini. Prolonged incubation with one of the peptides increased inhibition indicating a slow dissociation of the protease dimers. No cytotoxic effect of the inhibitors could be found below 200 micrograms/ml.

Amino Acid Sequence↗
PubMed1992

Study of color vision in fragile X syndrome.

Various theories have been postulated to account for the unusual inheritance pattern observed in the fragile X syndrome. The recent finding of a secondary amplification of the fragile X mutation in the offspring of carrier females [Oberle et al., 1991; Yu et al., 1991] is consistent with a maternal imprinting process. Laird [1987] has proposed that the fragile X mutation blocks complete reactivation of a previously inactivated fragile X chromosome. We have tested whether or not such a localized block extends as far distal as the red/green color-vision complex at Xq28. We found no evidence of color-vision defects among 25 male subjects with the fragile X syndrome. A fragile X positive woman also had normal color vision, despite being an obligate carrier of her father's gene for red/green color blindness. We conclude that the fragile X gene does not affect the function of neighboring color-vision genes, nor does it affect their ability to compensate adequately for inherited color deficiency on the homologous X chromosome in females.

Adolescent↗
PubMed1992

Peptide sequencing by matrix-assisted laser-desorption mass spectrometry.

A novel method of peptide sequencing by mass spectrometry is described. Metastable decay of laser-desorbed ions, taking place in the first field-free drift region of a reflection time-of-flight mass spectrometer, has been monitored to get structural information from larger peptides. Fragment ions from metastable decay are mass analysed by adjusting the potentials of the ion reflectron according to the kinetic energies of the ions. The features of the technique and its significance for future applications are outlined.

Amino Acid Sequence↗
PubMed1991

Joint occurrence of collagen mRNA containing cells and macrophages in human atherosclerotic vessels.

Cells with enhanced levels of collagen type I and III mRNA were identified and localized in frozen tissue sections from samples of human atherosclerotic renal and common iliac arteries by in situ hybridization using complementary 35S-labeled RNA probes. Serial sections were immunohistochemically stained for smooth muscle cells, monocytes, and differentiated macrophages. In the fibromuscular intima and in the fibrous plaques, cells with enhanced transcriptional activity were located mainly in the vicinity of differentiated macrophages. In three patients, lack of enhanced transcriptional activity in a proliferated intima was connected with complete absence of macrophages, thus indicating a quiescent stage of atherosclerosis. Immunohistochemical staining of serial sections for smooth muscle cells (SMC) revealed the presence of this cell type throughout the proliferated intima in atherosclerotic arteries including those areas in which enhanced collagen mRNAs were detected. The present results support the idea that macrophages play an important role in the activation of collagen synthesis in SMC of atherosclerotic vessel walls.

Adolescent↗
PubMed1990

Structural transition of alpha 1-antitrypsin by a peptide sequentially similar to beta-strand s4A.

Crystal structure studies have shown that cleaved and intact serpins differ essentially in the topology of beta-sheet A. This is five-stranded in the intact molecules and six-stranded after cleavage by insertion of strand s4A whose C-terminus has become free [Löbermann, H., Tokuoka, R., Deisenhofer, J. & Huber, R. (1984) J. Mol. Biol. 177, 531-556; Wright, T. H., Qian, H. X. & Huber, R. (1990) J. Mol. Biol. 213, 513-528]. The structural transition is accompanied by changes in spectral properties and an increase in thermal stability. We show here that an N alpha-acetyl-tetradecapeptide with the amino acid sequence of strand s4A, residues 345-358 of human alpha 1-antitrypsin, associates with intact alpha 1-antitrypsin and forms a stoichiometric complex with properties very similar to cleaved alpha 1-antitrypsin. Complex generation has the characteristics of a folding process.

Amino Acid Sequence↗
PubMed1990

Human anti-p68 autoantibodies recognize a common epitope of U1 RNA containing small nuclear ribonucleoprotein and influenza B virus.

Autoantibodies from patients with systemic rheumatic diseases were used to map antigenic sites on the 68-kD autoantigen (p68) associated with (U1)RNA-containing small nuclear ribonucleoprotein (snRNP) particles. With truncated recombinant fusion proteins and synthetic peptides, a subset of anti-p68 autoantibodies was found to recognize the amino acid sequence motif Glu-Arg-Lys-Arg-Arg (ERKRR). To investigate the possible involvement of epitopes shared by microbial antigens and host self-components in initiation of autoimmunity (molecular mimicry), a sequence data bank was screened for proteins containing an amino acid motif identical or related to ERKRR. The identical motif was found on the M1 matrix protein of influenza B viruses, and affinity-purified human anti-ERKRR autoantibodies recognized this epitope also in the viral amino acid sequence context. The common epitope recognized by human autoantibodies suggests that influenza B virus infection may play a role in initiation of the anti-p68 and anti-(U1)RNP autoimmune response.

Animals↗
PubMed1990

Localization of cytoplasmic collagen mRNA in human aortic coarctation: mRNA enhancement in high blood pressure-induced intimal and medial thickening.

Enhanced synthesis and deposition of extracellular matrix components, including collagen, contribute significantly to arteriosclerotic changes in the arterial vessel wall. We localized cells actively synthesizing collagen by hybridizing 35S-labeled RNA probes complementary to type I and III collagen mRNA with cytoplasmic mRNA in frozen sections of surgically removed aortic coarctations. These were chosen as a model for comparing mRNA levels in areas of high blood pressure-induced wall thickening and in unaffected post-stenotic areas. In situ hybridization revealed increased expression of type I and III collagen mRNA in intimal cells and in cells adjacent to the medial-adventitial border in the pre-stenotic part of the coarctation. In contrast, cells of the post-stenotic area showed only a very low signal. No immunohistologically detectable macrophages were seen in the pre-stenotic subendothelial areas where mRNA levels were enhanced. Higher collagen mRNA levels therefore occur in particular regions of high blood pressure-induced arterial wall thickening in the absence of macrophages. The results suggest that in situ hybridization is suitable for detection of locally occurring transcriptional activation of cells for collagens in the vessel wall.

Adolescent↗
PubMed1988

Complete cDNA sequence of a Dictyostelium ubiquitin with a carboxy-terminal tail and identification of the protein using an anti-peptide antibody.

The complete sequence of a Dictyostelium discoideum cDNA is presented that codes for monoubiquitin extended at its C-terminus by a 52 amino acid tail. The sequence of both the ubiquitin portion and the tail is highly homologous to the one of Saccharomyces cerevisiae and to a partial mouse sequence. The highly basic tail sequence contains a putative metal and nucleic acid-binding motif. The gene encoding the 0.6 kb mRNA of the C-terminally extended ubiquitin is represented only once in the haploid genome. The 0.6 kb mRNA as well as its translation product, a 15 kDa protein, is expressed in exponentially growing cells and remains present for at least 5 h of development. Using antibodies against a synthetic peptide that corresponds to the C-terminal amino acid sequence, a 15 kDa protein containing the extension a synthetic peptide that corresponds to the C-terminal amino acid sequence, a 15 kDa protein containing the extension was also detected in yeast.

Amino Acid Sequence↗
PubMed1982

(Alkyldithio)carbonyl groups for protection of amino functions in peptide synthesis.

(Alkyldithio)carbonyl groups were examined for their usefulness as amino-protecting groups in peptide chemistry. Among the derivatives studied, the (cyclohexyldithio)carbonyl function was found to be the most suitable for practical application. The related amino acid derivatives are obtained by relatively simple procedures and are sufficiently stable under normal conditions of peptide synthesis. Reductive cleavage with thiols or phosphines results in quantitative removal of this new amino protecting group.U

Acylation↗
PubMed1981

Hydrokinetic activity of secretion and secretin analogues, modified in the N-terminal sequence, and of vasoactive intestinal peptide in the dog pancreas.

In the dog pancreas in vivo, the biological activity of secretin and vasoactive intestinal peptide was compared to that of secretin analogues modified in their N-terminal hexapeptide and to X-secretion (alpha, beta-Asp3-secretin) and Y-secretin (a conversion product of X-secretin consisting of about 15% secretin and 85% beta-Asp3-secretin). Replacement of Asp3 by glutamic acid reduced secretin activity markedly. Replacement by neutral amino acids abolished the activity nearly completely. alpha, beta-Asp3-secretin and beta-Asp3-secretin appeared to be ineffective. The results indicate that the free beta-carboxy group of the side chain of the Asp3 residue of the secretin molecule is of decisive importance for hydrokinetic action.

Amino Acid Sequence↗
PubMed1981

[Total synthesis of somatostatin-28 (author's transl)].

The total synthesis of the octacosapeptide corresponding to the proposed primary structure of porcine somatostatin-28 is described. The synthesis has been performed using a protection scheme of maximum selectivity (acid labile side chain protection based on tert-butyl alcohol and 1-adamantol derived protecting groups in combination with the S-tert-butylthio group for reversible and selective blocking of the cysteine thiol functions and the 2-nitrophenylthio group for the temporary protection of the alpha-amino functions of intermediate segments) and of carefully selected fragments. Upon assembly in sequence order of the four suitably protected fragments related to sequences 18-28, 15-17, 8-14 and 1-7, the asymmetric disulfides were reduced by exposure of the fully protected octacosapeptide to phosphines. Subsequently, the final deprotection was performed with trifluoroacetic acid and the resulting dihydrosomatostatin-28 was then converted by air oxidation into the "cyclic peptide". Gel filtration on Biogel P-6 and ion-exchange chromatography on Biogel CM-2 produced somatostatin-28 at a high degree of purity. Comparative analysis of the synthetic and natural product by means of chromatographic, immunological and biological assays confirmed the structure proposed for this putative precursor of somatostatin-14.

Amino Acid Sequence↗
PubMed1981

[Total synthesis of human big gastrin I. Revised primary structure (author's transl)].

The synthesis of the tetratriacontapeptide amide corresponding to the revised structure of human big gastrin I is described. The fully protected peptide derivative was obtained by assembly in sequence order of the suitably protected fragments [1--9], [10--14] and [15--34] via the dicyclohexylcarbodiimide/N-hydroxysuccinimide and azide method, respectively. Upon removal of the protecting groups by exposure to trifluoroacetic acid and purification of the resulting crude product by chromatographic methods, human big gastrin I was obtained in satisfactory yields and at a high degree of purity. The identical immunological crossreactivities of natural and synthetic human big gastrin I using anti-porcine big gastrin I antiserum strongly supports the correctness of the newly proposed primary structure of this member of the gastrin family.

Amino Acid Sequence↗
PubMed1980

Evidence for a cyclic AMP system highly sensitive to secretin in gastric glands isolated from the rat fundus and antrum.

The effects of secretin and vasointestinal peptide (VIP) on the production of cyclic AMP have been studied in gastric glands isolated by means of EDTA from rat fundic and antral mucosa. (1) In gastric fundus, secretin and VIP caused a time- and temperature-dependent stimulation of cyclic AMP production that was maximal when the test agents were incubated for 60 min at 20 degrees C in the presence of 0.5 mM 3-isobutyl-1-methylxanthine as a phosphodiesterase inhibitor. The dose-response curve was monophasic for both peptides, the production of cyclic AMP being sensitive to 10(-10) M secretin and to 5 . 10(-8) M VIP. Half-maximal stimulation was obtained with 2.9 10(-9) M secretin or 2 . 10(-7) M VIP and the maximal stimulation represented a 21-fold and a 19-fold increase above control for secretin and VIP, respectively. Histamine also stimulated cyclic AMP production, with a Km of about 5 . 10(-4) M. No additive effect on cyclic AMP production was oberved when secretin and VIP were simultaneously added at maximally active concentrations, while an additive effect was observed when secretin and histamine were added together. (2) In gastric antrum, the characteristics of the secretin- and VIP-stimulated cyclic AMP production were similar to those observed in gastric fundus. Histamine nevertheless failed to stimulate the formation of cyclic AMP in antral mucosa. (3) These data demonstrate the existence of a cyclic AMP system highly sensitive to secretin in gastric glands isolated from the rat fundus and antrum and suggest that VIP operates through this system. (4) It is proposed that the pepsinogen- and/or mucous-secreting cells are implicated in the regulation of cyclic AMP production by secretin in gastric glands of the rat.

Animals↗