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G Kreil

Publications and source records attributed to G Kreil.

At least 37 records · Page 2Linked to original sources
PubMed1996

The TRH-like peptides in rabbit testis are different from the TRH-like peptide in the prostate.

Human seminal fluid contains a number of tripeptide amides with similar structures to thyrotropin releasing hormone (TRH), two of which have been identified as pGlu-Glu-Pro amide and pGlu-Phe-Pro amide. To determine whether these peptides originate in the same tissues and have the same molecular origin, TRH-immunoreactive peptides were extracted from the prostate and testis of the rabbit, purified by ion exchange chromatography and HPLC, and identified by co-chromatography with 3H-labelled marker peptides. In addition, trypsin digestion was used to release TRH-like tripeptides from N-extended forms of these peptides. The sole TRH-like peptide in the prostate was shown to be pGlu-Glu-Pro amide; it was not accompanied by a detectable amount of pGlu-Phe-Pro amide. The prostate also appeared to contain a very small amount of N-extended forms of these peptides. In contrast to the prostate, the testis contained high concentrations of N-extended forms of pGlu-Phe-Pro amide but essentially no tripeptide. The testis also contained N-extended forms of two other neutral TRH-like peptides which were less hydrophobic than pGlu-Phe-Pro amide. Neither the prostate nor the testis contained a significant amount of TRH. The results show that in the rabbit the TRH-like peptides pGlu-Glu-Pro amide and pGlu-Phe-Pro amide occur in different tissues and appear to be formed from different precursors.

Amino Acid Sequence↗
PubMed1996

BSTI, a trypsin inhibitor from skin secretions of Bombina bombina related to protease inhibitors of nematodes.

From skin secretions of the European frog Bombina bombina, a new peptide has been isolated that contains 60 amino acids, including 10 cysteine residues. Its sequence was determined by automated Edman degradation and confirmed by analysis of the cDNA encoding the precursor. A search in the databanks demonstrated that the pattern of cysteine residues in this skin peptide is similar to the ones found in protease inhibitors from Ascaris and in a segment of human von Willebrand factor. The 3D structure of the trypsin inhibitor from Ascaris suum could be used as a template to build a model of the amphibian peptide. In addition, we have demonstrated that this constituent of skin secretion is indeed an inhibitor of trypsin and thrombin, with K(i) values in the range of 0.1 to 1 microM. The new peptide was thus named BSTI for Bombina skin trypsin/thrombin inhibitor.

Amino Acid Sequence↗
PubMed1995

The precursors of the bee venom constituents apamin and MCD peptide are encoded by two genes in tandem which share the same 3'-exon.

From a cDNA library prepared from venom glands of worker bees, clones encoding the precursors of apamin and MCD peptide have been isolated. The cDNAs are similar at the 5'-ends and identical in their 3'-regions. Analysis of the corresponding genes has revealed the existence of six exons separated by introns rich in A + T. Starting from the 5'-end, these exons are arranged in the following order: three exons of the mast cell-degranulating (MCD) peptide precursor, two exons of the gene for the apamin precursor, and finally a 3'-exon present in both cDNAs. This suggests that the bulk of the apamin gene resides in the third intron of the MCD peptide gene. Using inverse polymerase chain reaction, a segment of genomic DNA upstream of the first exon of the MCD precursor gene was obtained. The sequence of this segment shows 81% identity to the DNA sequence preceding the first exon of the apamin gene and both contain a putative TATA box. We thus propose that the mRNA encoding the apamin precursor originates from a primary transcript which starts in the third intron of the MCD peptide gene. Both cDNAs encode unusually small precursors comprising only 46 amino acids in case of apamin and 50 in the case of the MCD peptide.

Amino Acid Sequence↗
PubMed1995

Hyaluronidases--a group of neglected enzymes.

Hyaluronan is an important constituent of the extracellular matrix. This polysaccharide can be hydrolyzed by various hyaluronidases that are widely distributed in nature. The structure of some bacterial and animal enzymes of this type has recently been elucidated. It could be shown that the hyaluronidases from bee and hornet venom and the PH-20 hyaluronidase present on mammalian spermatozoa are homologous proteins.

Animals↗
PubMed1995

Structure of two cDNAs encoding cholecystokinin precursors from the brain of Xenopus laevis.

The skin secretions of many frogs, including Xenopus laevis, contain caerulein, a peptide related to mammalian cholecystokinin. We have screened a cDNA library prepared from the brain of this frog using a cloned cDNA encoding one of the caerulein precursors as a probe. Two clones were isolated which contained inserts encoding cholecystokinin precursors. It was found that the predicted precursor polypeptides resembled their mammalian counterparts rather than the caerulein precursors from the same species. The corresponding mRNAs of different size encoding the Xenopus cholecystokinin precursors are expressed in brain and in the gastrointestinal tract, but not in skin. The smaller mRNA was also detected in lung. These data demonstrate that a polypeptide homologous to mammalian cholecystokinin precursors was present early in the evolution of vertebrates. The possible evolution of the genes encoding the more complex caerulein precursors is discussed.

Amino Acid Sequence↗
PubMed1994

Antimicrobial peptides from amphibian skin: an overview.

Over the past three decades, numerous peptides have been isolated from amphibian skin secretions. Many of these peptides were shown to be homologous to hormones and neurotransmitters of mammals. In recent years it has been shown that these secretions also contain a multitude of antimicrobial peptides. Most of these peptides are positively charged and have a propensity for forming an amphipathic helix. Other types of peptides have been detected as well, including one group which contain D-allo-isoleucine in their sequences. This work has mainly been done with three species from different families, Xenopus laevis, Bombina variegata and Rana esculenta. Each of these frogs produces distinct sets of peptides which are not related to those of other species. It can therefore be expected that many additional peptides with antimicrobial activity are present in amphibian species from other families.

Amino Acid Sequence↗
PubMed1993

The human sperm protein PH-20 has hyaluronidase activity.

The PH-20 protein present on the membrane of guinea pig sperm was characterized using a monoclonal antibody [(1991) J. Cell Biol. 111, 2939-2949]. We have isolated the cDNA encoding the human PH-20 protein from a testis library. This cDNA was expressed in RK 13 cells using a vaccinia virus expression system. Cells expressing the human PH-20 protein possess hyaluronidase activity. Treatment with PI-PLC releases the hyaluronidase into the the medium with a concomitant large increase in enzymatic activity. These results demonstrate that the human PH-20 protein has hyaluronidase activity.

Amino Acid Sequence↗
PubMed1993

Xenoxins, a family of peptides from dorsal gland secretion of Xenopus laevis related to snake venom cytotoxins and neurotoxins.

Three new, highly similar peptides from the skin secretion of Xenopus laevis have been purified and analyzed by mass spectrometry and Edman degradation. The 66-amino-acid peptides, termed xenoxin-1, -2, and -3, contain 8 cysteines and show similarity to snake venom cytotoxins and short neurotoxins. Assignment of two out of four disulfide bonds suggests a tertiary structure similar to that of cytotoxins and short neurotoxins. A cDNA encoding pre-xenoxin-1 was isolated from a X. laevis skin cDNA library. The nucleotide sequence predicts the synthesis of a precursor with a signal peptide followed by the sequence of the mature peptide. Xenoxin-1 and -2 lack alpha-neurotoxic activity, have apparently no antibacterial activity, are low in general toxicity as tested in mice, and have no effect on blood coagulation as measured in a Factor VIII procoagulant activity test. Potential functions of xenoxins as well as evolutionary aspects are discussed.

Activin Receptors↗
PubMed1993

Bee venom hyaluronidase is homologous to a membrane protein of mammalian sperm.

The venom of honeybees, Apis mellifera, contains several biologically active peptides and two enzymes, one of which is a hyaluronidase. By using degenerate oligonucleotides derived from the amino-terminal sequence of this hyaluronidase reported by others, clones encoding the precursor for this enzyme could be isolated from a cDNA library prepared from venom glands of worker bees. The deduced amino acid sequence showed that bee venom hyaluronidase is a polypeptide composed of 349 amino acids containing four cysteines and three potential sites for N-glycosylation. The sequence of the precursor also indicated that the conversion of the pro-enzyme to the end product must involve cleavage of a Thr-Pro bond, a most unusual processing reaction. The mRNA encoding hyaluronidase could also be detected in testes from drones. Expression of the cloned cDNA in Escherichia coli yielded a 41-kDa polypeptide that had hyaluronidase activity. Interestingly, the hyaluronidase from bee venom glands exhibited significant homology to PH-20, a membrane protein of guinea pig sperm involved in sperm-egg adhesion. These structural data support the long-held view that hyaluronidases play a role in fertilization.

Acrosome↗
PubMed1993

Antibacterial and haemolytic peptides containing D-alloisoleucine from the skin of Bombina variegata.

A family of bombinin-related peptides is present in the skin of Bombina variegata. These peptides contain 27 residues with Gly as N-terminus and display antimicrobial activity. From sequence analysis of the cDNAs encoding for the corresponding peptide precursors, the presence of a novel 20-residue peptide with Ile as N-terminus was predicted. We have now purified a family of hydrophobic peptides named H1-H5, whose sequences correspond to the predicted peptide with some variability in positions 1, 2 and 8. In particular, H3-H5 contain a D-alloisoleucine residue in the second position. All these peptides display antibacterial and haemolytic activity.

Amino Acid Sequence↗
PubMed1993

Frog prodermorphin expressed in mammalian cells is partly converted to the hydroxyproline containing precursor.

Using recombinant vaccinia virus, we have expressed in mammalian cells the cDNA coding for the precursor of dermorphin, a D-alanine containing opioid peptide from the skin of the South American frog Phyllomedusa sauvagei. HeLa cells and AtT-20 cells produced prodermorphin where proline-6 of dermorphin was partly hydroxylated. This was demonstrated by digesting the partially purified precursors with trypsin and carboxypeptidase B. After immunoprecipitation and separation by HPLC, two decapeptides were detected which differed by the presence of proline or hydroxy-proline at position 6. This demonstrates that HeLa cells as well as AtT-20 cells can perform the post-translational conversion of certain proline residues to hydroxyproline in a foreign hormone precursor expressed in these cells.

Amino Acid Sequence↗
PubMed1992

Isolation and sequence of a cDNA encoding the precursor of a bombesinlike peptide from brain and early embryos of Xenopus laevis.

A cDNA encoding the precursor of a bombesinlike peptide was isolated from brain of Xenopus laevis. The predicted end product resembles neuromedin B, which was originally isolated from mammalian spinal cord. The mRNA for this precursor was also present in gastrointestinal tract and in ovaries. Moreover, it could be detected in early embryos (stage 2 and stage 10) of X. laevis. These findings suggest novel roles for peptides of the bombesin family in oocyte maturation and early amphibian development.

Amino Acid Sequence↗
PubMed1992

Purification and properties of an iminopeptidase from culture media of Streptomyces plicatus.

The degradation of the prosequence of the secreted enzyme endo-beta-N-acetylglucosaminidase H from Streptomyces plicatus is not elucidated. Both the primary structure of this segment and the finding that the secreted species contain ragged aminoterminal ends of specific structure suggested that a dipeptidylaminopeptidase might mature this enzyme. Therefore, we tested the culture medium of Streptomyces plicatus for prolin-specific peptidases. Proline iminopeptidase was purified about 800-fold to homogeneity from the culture medium. Dipeptidylaminopeptidase, the enzyme that seemed most likely to process the prosequence of endo-beta-N-acetylglucosaminidase H, could not be detected.

Aminopeptidases↗
PubMed1992

Identification and characterization of two dermorphins from skin extracts of the Amazonian frog Phyllomedusa bicolor.

Skin extracts of South American hylid frogs of the subfamily Phyllomedusinae contain dermorphins and deltorphins, opioid heptapeptides highly selective for either mu or delta receptors. In all these peptides, a D-amino acid is present in the second position. The structure of the precursors for Ala-deltorphins was recently deduced from cloned cDNAs derived from skin of Phyllomedusa bicolor (Richter et al. (1990) Proc. Natl. Acad. Sci. USA 87, 4836-4839). From the amino acid sequence of these precursors, the existence of three peptides related to dermorphin could be predicted. From methanol extracts of skin of Ph. bicolor we have isolated two of these peptides, [Lys7]dermorphin-OH and [Trp4,Asn7]dermorphin-OH. The biological activity of these new dermorphins and their amidated counterparts is presented.

Amino Acid Sequence↗