An electrophoretically purified allophycocyanin-linker complex, AP⅐L C 7.8 , from phycobilisomes of Mastigocladus laminosus has been crystallized in the orthorhombic space group P2 1 2 1 2 1 . Cryocrystallographic x-ray measurements enabled the structural analysis of the complex at a resolution of 2.2 Å. The asymmetric unit contains two sideto-side associated ''trimeric'' (␣␤) 3 allophycocyanin complexes comprising the linker polypeptide in a defined orientation inside the trimer. The linker representing a protein fold related to the prosegment of procarboxypeptidase A is in contact with only two of the three ␤-subunits and directly interacts with the corresponding chromophores of these proteins. In addition to a modulation of the chromophores' spectral properties, the linker polypeptide attracts the ␣␤-subcomplexes, thereby bringing the ␤-chromophores closer together. These results will enable interpretations of energytransfer mechanisms within phycobiliproteins.

In the structure of the GST-glutathione complex, two conserved water molecules are observed, one of which hydrogen bonds directly to the sulphur atom of glutathione and the other forms hydrogen bonds with residues around the glutathione-binding site. These water molecules are absent from the structure of the Meisenheimer complex bound to GST, implicating that deprotonation of the cysteine occurs during formation of the ternary complex which involves expulsion of the inner bound water molecule. The comparison of our structures with known mu class GST structures show differences in the location of the electrophile-binding site (H-site), explaining the different substrate specificities of the two classes. Fluorescence measurements are in agreement with the position of the N-morpholino-ethansulfonic acid, close to Trp28, identifying a possible ligandin-substrate binding site.

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Indolmycin specifically prevents the formation of tryptophanyl-tRNA in a prokaryotic system in vifvo using Eschevichia coli enzymes. However, the drug has little effect in an eukaryotic system in v i m (rat liver enzymes). Analysis of the type of inhibition revealed that indolmycin competes with tryptophan as a pure competitive inhibitor of prokaryotic tryptophanyl-tRNA ligase.Most of the antibiotics inhibiting protein synthesis interfere directly with prokaryotic ribosomal functions. A small number of antibiotics act as inhibitors of steps taking place prior to translation (for review see [l]). For example, the drug borrelidin prevents the formation of threonyl-tRNA in some bacterial speciesIn this paper we show that indolmycin specifically inhibits the tryptophanyl-tRNA ligase from Escherichia coli whereas the corresponding ligase from rat liver is affected much less.PI. MATERIALS AND METHODS Muter ialsATP and tRNA from E. coli and calf liver were obtained from Boehringer, Mannheim ; the radioactive amino acids were obtained from New England Nuclear; Instagel scintillation liquid from Packard ; the filters from Sartorius ; the total synthesis of indolmycin followed described procedures [3 -61; all other chemicals were from Merck, Darmstadt. The 300000xg supernatant from rat liver was a generous gift from Dr F. Grummt

The polyunsaturated fatty acid composition of colostrum in a high risk newborn population shows associations with atopic sensitization at the age of 1 year and may be predictive for later atopic disease.

Phycobiliproteins and phytochromes are light-harvesting and light-sensing proteins containing linear tetrapyrroles, so-called bile chromophores. The chromophores in certain biliproteins, including the phytochromes, isomerize reversibly from a stable Z-configuration to a stable E-configuration when irradiated with light of the appropriate wavelength. Here, we report the crystal structure of alpha-phycoerythrocyanin with its chromophore in the E-configuration, compare it with the Z-configuration found in trimeric phycoerythrocyanin, and reveal the structural bases of the isomerization. The geometric changes of the chromophore account for the large spectral shift, which characterizes the overall transition. Interactions of the chromophore A and D pyrrole rings with flexible protein moieties are required for the formation and stabilization of the isomers. We predict that the results will hold for all photoactive biliproteins.

Background: Elevated levels of circulating cell adhesion molecules (cCAMs) such as vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and endothelial leukocyte adhesion molecule-1 (E-selectin) are found in subjects with vascular diseases and in subjects with several risk factors for atherosclerosis. However, data evaluating cCAMs and biological age are limited. Objective: The purpose of this study was to assess in subjects with different cardiovascular risk profiles the levels of cVCAM-1, cICAM-1, and cE-selectin in dependence on age. Methods: The following groups of subjects were included in the study: 282 apparently healthy subjects of the average population aged 18–89 years, 77 vegetarians who are characterized by a favourable global cardiovascular risk profile, 94 patients with coronary heart disease, and 181 patients with peripheral arterial occlusive disease. Blood samples were obtained after an overnight fast for measurement of cCAMs, lipoproteins, and other clinical/biochemical parameters. The cCAM levels were determined by the use of monoclonal antibody based enzyme-linked immunosorbent assays. Results: Amongst the cCAMs, cVCAM-1 is uniquely elevated in elderly persons with different risks for atherosclerosis, including subjects of the average population, vegetarians with a favourable risk profile, and patients with both coronary heart disease and peripheral arterial occlusive disease. With respect to cICAM-1, an age-dependent elevation was found in the control subjects included in the study. The cE-selectin levels were not correlated with age. Moreover, no associations of cCAMs with serum lipid and lipoprotein levels were found. Conclusion: The results of the present study indicate that cVCAM-1 is an age-dependent parameter independent of cardiovascular risk.

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