On the basis of our recent results, the N‐terminal sequence of HIV‐1 Tat protein as a natural competitive inhibitor of dipeptidyl peptidase IV (DP IV) is supposed to interact directly with the active site of DP IV hence mediating its immunosuppressive effects via specific DP IV interactions. Of special interest is the finding that amino acid substitutions of the Tat(1–9) peptide (MDPVDPNIE) in position 5 with S‐isoleucine and in position 6 with S‐leucine led to peptides with strongly reduced inhibitory activity suggesting differences in the solution conformation of the three analogues. Therefore, 1H NMR techniques in conjunction with molecular modelling have been used here to determine the solution structure of Tat(1–9), I5‐Tat(1–9) and L6‐Tat(1–9) and to examine the influence of amino acid exchanges on structural features of these peptides. The defined structures revealed differences in the conformations what might be the reason for different interactions of these Tat(1–9) analogues with certain amino acids of the active site of DP IV.

Two new peptide alkaloids, scutianines-K and -L were isolated from Scutia buxifolia, a plant growing in Brazil, Argentina and Uruguay. Their structures have been determined on the basis of spectroscopic studies. The stereochemistry of the N,N-dimethyl amino acid side-chain and the ring amino acid residues in both alkaloids have been assigned by gas chromatography employing modified cyclodextrins as chiral stationary phases.

A new jasmonate, N-[(—)-jasmonoyl]-tyramine, was identified from petunia pollen in which (—)-jasmonic acid was detected and quantified.

Incorporation of [1-13C]- and [U-13C6]glucose indicates that the biosynthesis of sesquiterpenoid cyclohexenone derivatives in mycorrhizal barley roots proceeds via the glyceraldehyde 3-phosphate/pyruvate non-mevalonate pathway.Incorporation of label from [1-13C]glucose (•) and [U-13C6]glucose ( − ) into the aglycon part (blumenol C) of blumenin indicates that in barley roots the arbuscular mycorrhizal fungus Glomus intraradices induces the glyceraldehyde 3-phosphate/pyruvate non-mevalonate pathway leading to sesquiterpenoid cyclohexenone derivatives.

In addition to (-)-mehranine, hecubine, ibogaine, ibogaline, 19R-epi voacristine, 20-hydroxyconopharyngine and pedunculine the novel indole alkaloids 3-oxomehranine and 14α,15β-dihydroxy-N-methylaspidospermine have been isolated from the leaves and stems of Tabernaemontana bovina. The structure of 3-oxomehranine has been assigned by NMR investigations, the structure of 14α,15β-dihydroxy-N-methylaspidospermine by X-ray analysis and their absolute configurations by circular dichroism.

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Exogenously applied 3-dehydro-24-epi-teasterone is transformed by cell suspension cultures of Lycopersicon esculentum to give the metabolites 24-epi-teasterone and 24-epi-typhasterol in about equal but low quantities. The major portion of 24-epi-teasterone was found as carbohydrate conjugates while 24-epi-typhasterol occurred in free form, indicating significant influence of glycosidation on the equilibrium between both compounds. The importance of these conjugation processes for the regulation of the brassinosteroid biosynthesis is discussed.In tomato cell cultures, 3-dehydro-24-epi-teasterone is transformed both to 24-epi-teasterone and 24-epi-typhasterol. The ratio between both epimers is regulated by glycosidation in 3β-position

The platina‐β‐diketone [Pt2{(COMe)2H}2(μ‐Cl)2] (1 ) reacts with aliphatic amines [n BuNH2, (i Pr)2NH, NEt3], N‐methylaniline, and N ,N‐dimethylaniline, as well as with strong bases, such as a proton sponge or [NMe4]OH, in an equimolar ratio to give the anionic platina‐β‐diketonato complexes of platina‐β‐diketones [BH]2[{Cl2Pt(μ‐COMe)2Pt[(COMe)2H]}2] (3 ) {B = n BuNH2 (3a ), (i Pr)2NH (3b ), NEt3 (3c ), PhNHMe (3d ), PhNMe2 (3e ), C10H6(NMe2)2 [1,8‐bis(dimethylamino)naphthalene] (3f ) and [NMe4]2[{Cl2Pt(μ‐COMe)2Pt[(COMe)2H]}2] (3g )}. All complexes were characterized by microanalysis, and by 1H‐NMR and IR spectroscopy. X‐ray structure analyses reveal that in the solid state the complexes 3a · 0.5 CH2Cl2 and 3g · 2 CH2Cl2 consist of tetranuclear dianions with zigzag Pt4 chains [Pt–Pt–Pt angle: 122.92(3)° (3a ), 119.30(6)° (3g )]. The central Pt···Pt distances [3a : 3.171(1) Å, 3g : 3.176(1) Å] give evidence for closed shell d8‐d8 interactions. Thus, these bis(acyl)‐bridged complexes can be regarded as organometallic analogues of platinum blue complexes.

Lipoxygenases (LOXs) and other LOX pathway enzymes are potentially able to form a large set of compounds being of commercial interest. Among them are conjugated dienic acids, jasmonates, and volatile aldehydes. Additionally, fatty acid hydroperoxides, formed by LOX, can serve as precursors for further transformation by either enzymes of the so‐called LOX pathway or by chemical reactions. In the case of linoleic acid more than one hundred products generated from its LOX‐derived fatty acid hydroperoxides have been described. Many of these products exhibit biological activity, suggesting a significant biological function of LOXs. This will be described for two different 13‐LOXs. (I) In various oilseeds we found that specific 13‐LOXs are localized at the lipid body membrane. They are capable of oxygenating esterified polyenoic fatty acids, such as triacylglycerols and phospho‐lipids. In addition, they form with arachidonic acid as substrate preferentially either 8‐ or 11‐hydroperoxy eicosatetraenoic acid, which is a very unusual positional specificity for plant LOXs. (II) From barley leaves we isolated another linoleate 13‐LOX form, which is localized within chloroplasts and is induced by jasmonic acid methyl ester. It is suggested, that this LOX form is capable of oxygenating linolenic acid residues of galactolipids. Examples will be presented for barley leaves of oxygenated derivatives of linolenic acid and compounds resulting from the hydroperoxide lyase‐branch of the LOX pathway.

Human cathepsins K and S are recently identified proteins with high primary sequence homology to members of papain superfamily, including cathepsins B, L, H and papain. Models of the tertiary structures of cathepsins K and S and their complexes with a specific substrate and inhibitor were constructed and compared with the recently determined X-ray structure of cathepsin K. A major problem in the determination of the three-dimensional structure of proteins concerns the quality of the structural models obtained from the interpretation of experimental data. The framework of the tertiary structures of cathepsins K and S consisted of structurally conserved regions from the tertiary structure of the papain superfamily and the variable regions were constructed with fragments of other proteins from the protein data base. Based on docking studies the non-bonded interaction energies of ligands with the cathepsins were estimated. These energies correlate with experimentally determined substrate and inhibitory potency.