Axel Zeeck

was born in Rummelsburg (Pomerania, today in Poland) in 1939 and studied chemistry at the Georg August University Göttingen. He obtained his Ph.D. in 1966 under the guidance of H. Brockmann. In 1974 he finished his habilitation also in Göttingen, where he became assistant professor of organic chemistry in 1980. In 1999 he was appointed full professor of Biomolecular Chemistry.

He is coordinator of the Lower Saxony research focus “Marine Biotechnology” and is responsible for the chemical education of medical students. In this context, he is author of the book Chemie für Mediziner (Chemistry for Medical Students) (Urban & Fischer, 4th ed., 2000). In 1994 he was awarded the Max Planck Research Award of the Max Planck and the Alexander von Humboldt Society – one of the most reputable German scientific awards – for his exploration of the mechanism of the effect of bafilomycin and concanamycin on the V-type ATPase. He is the author of some 150 publications; 35 patents have been issued to him.

Scientific Sketch

Microorganisms are an important source of novel natural products such as antibiotics and other active substances. For the isolation of chemically new and biologically active compounds, the group of Zeeck cultivates especially actinomycetes, streptomycetes, and fungi imperfecti. In the search for new secondary metabolites, both the biological and the chemical screening have been applied with success. For the latter either thin-layer chromatography (TLC) with different types of staining reagents or HPLC with varying detection methods (UV, MS, CD) is used to record all metabolites produced in the culture extracts. Most of the strains evaluated in Zeeck’s group are isolated from earth samples and are cultivated in fer-menters of up to 50 liters.

As a result of such efforts, hexacyclinic acid, a natural product of highly complex structure, has been isolated and characterized recently (Fig. 1,Angew. Chem. Int. Ed. 2000, 39, 3258).

Figure 1. Hexacyclinic acid, from S. cellulosae.

The chemical work starts with the isolation and structure elucidation of the novel natural products. Structural problems are solved by using modern spectroscopic methods (e.g., MS, high field 2D-NMR, X-ray analysis). Zeeck and co-workers have revealed the structures of several hundreds of metabolites that belong to different chemical classes (e.g., peptides, macrolides, quinones, glycosides, and polyenes).

Further investigations focus on the biosynthesis of the discovered compounds, starting with feeding experiments using stable isotope precursors. Thus, the biosynthesis of kendomycin, a polyketide isolated from Streptomyces vio-laceoruber with a unique structure, was disclosed. This molecule shows antiosteoporotic properties and is an inhibitor of endothelin receptors. By using feeding experiments with marked precursors, the biosynthesis was elucidated (Fig. 2, J. Chem. Soc. Perkin Trans. 1 2000, 323 and 2665).

Figure 2. Kendomycin, from S. violaceoruber.

The group is interested in new biosynthetic pathways and tries to modify the metabolites by applying the precursor-directed biosynthesis and by changing the cultivation conditions (OSMAC approach, ChemBioChem 2002, 3, 619). The biological activity of the metabolites and derivatives is established in different test systems, mostly in cooperation with colleagues and industry.

Filled Peppers à la Benjamin

Starting materials (serves 2):

bell peppers (yellow or red, 1–2 per person)

crumbled brown bread

crème fraîche

curry powder

herbs

1–2 eggs

double cream

cheese slices

salt

1) Wash the peppers and hollow them out from the stem so that a hole for the filling is formed.

2) Fill half of the pepper with the crumbled wholewheat bread.

3) Prepare the rest of the filling in a separate bowl: crème fraîche, salt, curry, herbs, eggs, some double cream.

4) Pour filling into the pepper and add some more crumbled bread if necessary.

5) Cover the opening with a slice of cheese.

6) Put the filled peppers into a pot and add so much vegetable broth that the lower half of them is plunged. Boil 15–20 minutes with closed lid until the peppers are soft.

To be served with rice or millet.

«Being short on time due to changing the diapers, nursing, comforting, and carrying, this recipe originates from the plight, after the birth of our son Benjamin (14.10.2001), to bring something palatable and vegetarian onto the table.

Meanwhile, we are both capable of preparing this dish, but the result is always slightly different, which might result from a different handling of the spices..»

Sabine Fischer & Axel Zeeck