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Biomedical subjects

G Kreil

Publications and source records attributed to G Kreil.

At least 91 records · Page 5Linked to original sources
PubMed1979

Further studies on the structural requirements for polypeptide-mediated histamine release from rat mast cells.

Structure-activity studies have been performed on a series of naturally occurring and 'tailor-made' polypeptides, by measurement of ability to induce selective histamine release from normal rat peritoneal mast cells in vitro. Compounds investigated include corticotropin and melittin derivatives, mast-cell-degranulating peptide from bee venom, polymyxin B, bradykinin and various synthetic poly(amino acids) and short-chain peptides. It was confirmed that a cluster of four basic residues (lysine or arginine) was optimal for histamine release by corticotropin and melittin polypeptides, provided that the C-terminal carboxyl group was substituted (by, for instance, amidation). In contrast, the presence of a free C-terminal carboxyl group or nearby dicarboxylic acid residues led to a considerable diminution in histamine-releasing activity. Likewise, polypeptides comprised essentially of acidic amino acids were inactive. On the basis of these observations it has been possible to predict that synthetic peptides comprising a particular sequence within the Fc region of human immunoglobulin E, the immunoglobulin class particularly involved in mediation of allergic reactions of the immediate type, would possess potent histamine-releasing activity when similarly made to react with normal rat mast cells. The further study of such a structure should throw new light on the molecular basis of allergen-antibody triggering of mast cells.

Adrenocorticotropic Hormone↗
PubMed1978

Amino acid sequence of honeybee prepromelittin synthesized in vitro.

Translation of melittin messenger RNA from queen bee venom glands in a cell-free system from wheat germ yielded prepromelittin. Sequence analysis of the labeled in vitro product was performed by automatic Edman degradation of the intact polypeptide as well as by analysis of some of its proteolytic fragments. Prepromelittin was shown to be composed of 70 amino acids, two of which have not been identified. The sequence of melittin is located in the COOH-terminal third of the polypeptide chain (residues 44--69). Prepromelittin starts with a very hydrophobic pre-region, probably 21 residues long, followed by a pro-part of unusual sequence, containing only alanine, proline, and acidic residues. At least three post-translational reactions are required to convert prepromelittin to mellitin.

Amino Acid Sequence↗
PubMed1977

Honey bee venom melittin: correlation of nonspecific inflammatory activities with amino acid sequences.

The nonspecific (nonallergic) inflammatory activity of melittin, a protein toxin from honeybees, was correlated with specific amino acid sequences. Two different amino acid sequences of melittin were found to contribute to nonspecific inflammatory activities in guinea pig skin. Carboxy terminal peptide sequences of 7--10 amino acids induced immediate inflammatory reactions that reached maximum intensities by 15--30 min, then rapidly dissipated. The amino (N) terminal hydrophobic sequence, although not directly inflammatory, intensified the immediate reaction, causing a severe lesion evident by 2 h and characterized by massive polymorphonuclear leukocyte infiltration. A conceptual model of bee venom-induced inflammation in nonallergic individuals is suggested.

Amino Acid Sequence↗
PubMed1977

Translation of melittin messenger RNA in vitro yields a product terminating with glutaminylglycine rather than with glutaminamide.

Melittin messenger RNA from queen bee venom glands has been translated in a cell-free system from wheat germ. A product larger than promelittin is formed which has the carboxy-terminal sequence-Gln-Gln-GlyCOOH. Melittin and promelittin from venom glands terminate in -Gln-GlnCONH2. The possible role of the extra glycine residue in the formation of a COOH-terminal amide via a transamidase-like reaction is discussed.

Amino Acid Sequence↗
PubMed1976

Action of phospholipases on the cytoplasmic membrane of Escherichia coli. Stimulation by melittin.

The emission maximum of the single tryptophan residue of melittin was measured in the presence of phosphatidylethanolamine liposomes and Escherichia coli cytoplasmic membranes. In both cases, the fluorescence maximum was shifted to shorter wavelengths indicating a transfer of the indole ring to an apolar environment. E. coli membranes were labelled in position 2 of their phospholids with [14C]oleic acid. These membranes were used for measuring the activity of an endogenous phospholipase A2. A slow hydrolysis is observed, which can be accelerated by adding melittin. The extent of the stimulation depends on the molar ratio of melittin to membrane phospholipid. Under suitable conditions, the initial rate of hydrolysis is six to seven times higher in the presence than in the absence of melittin. The action of the phospholipase A2 from bee venom is also stimulated by melittin. An identical stimulation was observed with either E. coli membranes or pure phosphatidylethanolamine liposomes as substrate.

Cell Membrane↗
PubMed1975

Translation of honeybee promelittin messenger RNA. Formation of a larger product in a mammalian cell-free system.

Venom glands of honeybees synthesize the peptide melittin via the precursor promelittin. Total RNA preparations from venom glands served as template in a cell-free system prepared from mammalian cells. The heterologous system translated the insect mRNA with approximately the same efficiency as hemoglobin mRNA. A polypeptide was synthesized which, as shown by acrylamide gel electrophoresis in the presence of detergent, has a higher molecular weight than promelittin. Analysis of peptic fragments as well as Edman degradation have demonstrated that sequences characteristic of venom gland promelittin are present in this product formed in vitro. Furthermore, a bacterial protease which specifically splits after acidic residues liberates from the cell-free product a fragment which closely resembles melittin. Evidence is presented that most of the extra amino acids are located at the amino terminus of the product formed in vitro. The larger polypeptide detected in vitro may represent a precursor of promelittin.

Amino Acid Sequence↗
PubMed1975

[Characteristics of the phlogistic action of melittin, its C-terminal fragment and some basic peptides in the rat paw (author's transl)].

Injection into the rat paw of either melittin, its C-terminal dekapeptide, tetralysine or triarginine causes an inflammatory response with melittin having the highest and the last mentioned peptides the lowest activity. The inflammatory action of melittin and the dekapeptide has the following characteristics: 1. it is mainly due to the liberation of histamine, since on both compounds the anti-histaminic diphenhydramine has a pronounced inhibitory effect; 2. di-sodium-cromoglycate inhibits only the inflammatory action of the dekapeptide but has no effect on the activity of melittin. Melittin and its fragment thus liberate histamine via different routes.

Animals↗