Wolfram Schäfer

Darstellung Geschützter Peptid-Fragmente unter Einsatz substituierter Triphenylmethyl-Harze

Zusammenfassung Substituted triphenylmethyl(trityl) resins have been tested for their applicability for the synthesis of protected peptide fragments. Among them the 2-chlorotrityl resin 3c fulfills all requirements needed to obtain the desired fragments in high yield and purity, using Fmoc-amino acids protected at their side chains with groups of the t-butyl type.

Immunologically active polysaccharides of Echinacea purpurea cell cultures

Abstract From the medium of Echinacea purpurea cell cultures three homogeneous polysaccharides, two neutral fucogalactoxyloglucans with mean M r of 10 000 and 25 000 and an acidic arabinogalactan with a mean M r of 75 000, have been isolated by DEAE-Sepharose CL-6B, DEAE-Trisacryl M and Sephacryl S400 column chromatography. Their structures were elucidated mainly by methylation analysis, partial acidic and enzymatic hydrolysis and 13 C NMR spectroscopy. The fucogalactoxyloglucan of mean M r 25 000 enhances phagocytosis in vitro and in vivo . The arabinogalactan specifically stimulates macrophages to excrete the tumour necrosis factor (TNF).

Di-myo-inositol-1, 1′-phosphate: A new inositol phosphate isolated from Pyrococcus woesei

A new inositol derivative could be isolated from the Archaeum Pyrococcus woesei and identified as di‐myo‐inositol‐1,1′‐phosphate by 1H, 31P NMR spectroscopy, mass spectrometry and thin layer chromatograpy. In P. woesel, this inositol phosphate represents the dominant counterion of K+ which ranges from 500 to 600 mM. The role of the potassium salt of di‐myo‐inositol‐1,1′‐phosphate as thermostabilizer is discussed.

Veresterung von partiell geschützten peptid-fragmenten mit harzen. Einsatz von 2-chlortritylchlorid zur synthese von Leu15 -gastrin I

Zusammenfassung The esterification of several partially protected peptide fragments through the C-terminal or a free side chain carboxy group with hydroxy groups containing resins and the 2-chlorotritylchloride resin 8 is described. As an application example crude protected Leu 15 - gastrin I ( 15a ) has been obtained in 99% yield by the “solid-phase” method using 8 as the solid support. Crude 15a has been deprotected to free Leu 15 - gastrin ( 16 ) which is thus obtained in 92% yield and 90% purity.

The complete primary structure of the spermadhesin AWN, a zona pellucida-binding protein isolated from boar spermatozoa

AWN is a boar protein which originates in secretions of the male accessory glands and which becomes sperm surface‐associated upon ejaculation. It is one of the components thought to mediate sperm adhesion to the eggs zona pellucida through a carbohydrate‐recognition mechanism. AWN may, thus, participate in the initial events of fertilization in the pig. In this report we describe its complete primary structure by combination of protein‐chemical and mass spectrometric methods. AWN exists as two isoforms, AWN‐1 and AWN‐2, which differ in that AWN‐2 is N‐terminally acetylated. The amino acid sequence of AWN contains 133 amino acid residues and two disulphide bridges between nearest‐neighbour cysteine residues. Analysis of the amino acid sequence of the AWN proteins showed significant similarity only to AQN‐1 and AQN‐3, two other boar spermadhesins.

Boar spermadhesin PSP-II: Location of posttranslational modifications, heterodimer formation with PSP-I glycoforms and effect of dimerization on the ligand-binding capabilities of the subunits

Spermadhesin PSP‐II was isolated from the non‐heparin‐binding fraction of boar seminal plasma; its disulphide bridge pattern, and the location of a single N‐glycosylation site were established. PSP‐II forms a heterodimer with specific N‐glycoforms of PSP‐I. Although both subunits possess heparin‐binding capability, the PSP‐I/PSP‐II complex does not. The heterodimer contains binding sites for zona pellucida glycoproteins and soybean trypsin inhibitor located in the PSP‐II subunit. However, the PSP‐I/PSP‐II heterodimer binds only loosely to the sperm surface and is easily removed during in vitro capacitation, suggesting that the zona pellucida binding activity may not be relevant for gamete interaction. Our results show that dimerization of spermadhesins PSP‐I and PSP‐II markedly affects their binding capabilities.

Conversion of aniline into pyrocatechol by a Nocardia sp.; incorporation of oxygen-18

A great number of the numerous pesticides which enter the environment are aniline derivatives. The biochemical transformation of anilines in soil [l-4] , in the liver microsome system [5-71, and by pure cultures of microorganisms [8], has been studied, but the pathway of aniline degradation by soil microorganisms is still unknown. Therefore, the conversion of aniline into pyrocatechol by a mutant strain of a Nocarclia sp. was studied in an atmosphere of l8 Oz. The results suggest that both atoms of oxygen in the pyrocatechol were derived from molecular oxygen.

The disulfide bridge pattern of snake venom disintegrins, flavoridin and echistatin.

Flavoridin and echistatin, isolated from the venom of Trimeresurus flavoviridis and Echis carinatus, respectively, belong to the disintegrin family of integrin β1 and β3 inhibitors of low molecular weight RGD‐containing, cysteine‐rich peptides. Since disulfide bonds are critical for expression of biological activity, we sought to determine their location in these two proteins. In flavoridin, direct evidence for the existence of linkage between Cys4‐Cys10 and between Cys45 and Cys64 was obtained by analysis of proteolytic products, and indirect evidence suggests links between Cys13‐Cys14 and Cys13‐Cys14. In echistatin, links between Cys14‐Cys37 and Cys20‐Cys34 were identified by direct chemical analysis.

Derivation of the formyl-group oxygen of chlorophyll b from molecular oxygen in greening leaves of a higher plant (Zea mays)

Using mass spectroscopy, we demonstrate as much as 93% enrichment of the 7‐formyl group oxygen of chlorophyll b when dark‐grown, etiolated maize leaves are greened under white light in the presence of 18O2. This suggests that a mono‐oxygenase is involved in the oxidation of its methyl group precursor. The concomitant enrichment of about 75% of the 131‐oxygen confirms the well‐documented finding that this oxo group, in both chlorophyll a and b, also arises from O2. High 18O enrichment into the 7‐formyl oxygen relative to the substrate 18O2 was achieved by optimization of the greening conditions in combination with a reductive extraction procedure. It indicates not only a single pathway for Chl b formyl group formation, but also unequivocally demonstrates that molecular oxygen is the sole precursor of the 7‐formyl oxygen.

Occurrence of methylated amino acids as N-termini of proteins from Escherichia coli ribosomes

Ribosomal proteins of Escherichia coli have been shown for the first time to be methylated at the α-amino group of the protein chain. The N-termini determined are N -monomethyl-alanine in S11 and L33 and N -monomethyl-methionine in L16. The amino acids with secondary amino groups give low extinction at 590 nm after reaction with ninhydrin. Although the above proteins are monomethylated at their N-termini they are accessible to the Edman degradation process.