Wolf-Dietrich Woggon

The substrate specificity of tocopherol cyclase

The substrate specificity of the enzyme tocopherol cyclase from the blue-green algae Anabaena variabilis (Cyanobacteria) was investigated with 11 substrate analogues revealing the significance of three major recognition sites: (i) the OH group at C(1) of the hydroquinone, (ii) the (E) configuration of the double bond, and (iii) the length of the lipophilic side chain. Experiments with two affinity matrices suggest that substrates approach the enzymes active site with the hydrophobic tail.

Transfer of cantharidin (1) during copulation from the adult male to the femaleLytta vesicatoria (‘Spanish flies’)

Adult males of the ‘spanish fly’Lytta vesicatoria (Meloidae, Coleoptera) are able to biosynthesize cantharidin (1) ‘in copula’ after injection of E, E-11′-(3H,14C)-farnesol and 2-14C-methylfarnesoate. During mating, the cantharidin biosynthesized in the males is transferred to the females, who are unable to biosynthesize cantharidin from any terpenoid precursors. After injection of (3H,14C)-cantharidin into males during copulation, more than 10% is transferred into the female sex organs. Males injected with 2-(3H,14C)-mevalonate 24–30 h prior to copulation transferred 93–98% of the biosynthesized cantharidin to the females during mating. After mating, the males continue to produce cantharidin. It seems that in the male the biosynthesis of cantharidin is stimulated during copulation.

On the Origin of the Low‐Spin Character of Cytochrome P450cam in the Resting State—Investigations of Enzyme Models with Pulse EPR and ENDOR Spectroscopy

The P450 enzyme model 1 is a high-spin system. EPR and ENDOR spectra reveal the coordination of water to the FeIII center. This is the first experimental proof that coordination of water is not the single determining factor in the stabilization of the low-spin character of the cytochrome P450 resting state.

The synthesis of a new active-site analogue of cytochrome P450 carrying substrate recognition sites and athiolate ligand

Abstract The synthesis of a new mono-bridged iron(III)porphyrin 2 is described which contains all structural elements significant to an active-site analogue of cytochrome P450: (i) a thiolate ligand coordinating to the iron, and (ii) a substrate-recognition site provided by two substructures derived from Kemps acid which are positioned perpendicular to the porphyrin plane. 1 H-NMR experiments show that esters like dimethyl glutarate bind with K = 137 M −1 .

Biosynthesis of cantharidin: evidence for the specific incorporation of C-4 and C-11′ of farnesol

(E,E)-[11′,12-3H2,2,4-14C]farnesol is specifically incorporated into cantharidin as shown by use of a new degradation involving a Diels–Alder/retro-Diels–Alder sequence; the incorporation of (E,E)-[11′-3H, 14C,2-14C]-farnesol (14) into cantharidin proceeds with 47%3H-retention whereby the 11′-14C label is randomised at C-9 and C-11 in cantharidin and the ratio [2-14C]/[11′-14C] of (14) is retained indicating an intramolecular conversion of farnesol into cantharidin.

Biosynthesis of vitamin B12: structure of the trimethylisobacteriochlorin from Propionibacterium shermanii

N.m.r. and chemical studies on a family of related macrocycles lead to structure (7a), having C-methylation at C-20, for the trimethylisobacteriochlorin from P. shermanii.

The mechanism of allylic oxidation by selenium dioxide

In the course of the SeO2-oxidation of 5-cyclopentyl-2-methyl[1-13C]pent-2-ene and its isotopomer (2), which stereoselectively yields the E-products (7)–(10), the 13C label is distributed between C-1 and the C-2 substituent, indicating that two separate steps in the sequence determine the stereochemical features of the products; the ene-reaction proceeds in favour of the trans-methyl-group of the olefin by a factor of 7 : 3 and the following [2,3] sigmatropic rearrangement generates the E-configuration of the resulting alcohols.

The synthesis of a cytochrome c analogue

The doubly-bridged iron porphyries (1) and (8) have been synthesized carrying a covalently bound, proximal S–Me ligand and an imidazole co-ordinating to the iron; UV and 1H NMR spectroscopy and electrochemistry show that compounds are close analogues of cytochrome c.