Evidence for an extended interacting surface between beta-amyloid and serum amyloid P component.

Studying the interaction between serum amyloid P component (SAP) and beta-amyloid (Abeta) a new Abeta binding site was identified on the SAP near the known binding site at the two bound calcium ions. SAP stabilizes deposits in neurodegenerative diseases, which is manifested via Abeta-binding. Because the inhibition of this interaction is a potential therapeutic target in neurodegeneration, the structural basis of SAP-Abeta binding was studied.

Steroid epimers studied by different mass spectrometric methods.

The combined use of different mass spectrometric ionization methods and MS/MS techniques provide the possibility to differentiate between stereoisomers or epimers. In this paper the mass spectral decomposition of 11alpha- and 11beta-substituted estrans was studied. Distinctive stereochemical effects have been observed in their fast atom bombardment product ion spectra.

A new ecdysteroid with unique 9beta-OH and four other ecdysteroids from Silene italica ssp. nemoralis.

A new natural ecdysteroid, 9beta,20-dihydroxyecdysone (1) and four related compounds 5alpha-20-hydroxyecdysone (2), 5alpha-2-deoxy-integristerone A (3), integristerone A (4) and 22-deoxy-integristerone A (5) were isolated from the herb of Silene italica ssp. nemoralis. Compound 1 is the C-9 epimer of the known 9alpha,20-dihydroxyecdysone (6) and represents a peculiar steroid skeleton.

Two new ecdysteroids from Serratula wolffii.

11alpha-Hydroxypoststerone (1) and herkesterone (2), two new natural ecdysteroids, were isolated from the herb Serratula wolffii. The former compound is the first 11-hydroxylated C21 ecdysteroid, while the latter is a new ecdysteroid with a 7,9(11)-dien-6-one chromophore. Their structures were determined using a combination of spectroscopic techniques.

Stereoselective reactions of (20R)-3,20-dihydroxy-(3',4'-dihydro-2'H-pyranyl)-5-pregnene derivatives form 27-nor-3,20,23,26-tetrahydroxy-cholesten-22-ones and related bromo ketones.

The previously reported analog of pregnenolone having a 3,4-dihydro-2H-pyran attached via a Cz.sbnd;C bond to the C-20 position (1), stereoselectively reacts with m-chloroperoxybenzoic acid in methanol at -5 degrees C. Acid-catalyzed hydrolysis of the isolated intermediates gives good yields of mostly a new 27-norcholesterol analog: (20R,23R)-3,20,23,26-tetrahydroxy-27-norcholest-5-en-22-one-3-acetate (2a, and a smaller amount of its 23S enantiomer 2b).

Hydrolytic behavior of 5alpha-hydroxy-11beta- and 5beta-hydroxy-11alpha-substituted 19-norsteroids.

Teutsch G. and Bélanger A. treated 5alpha,10alpha epoxides with Grignard-reagents catalyzed by copper(I) ions.

Cryo-bioorganic chemistry: freezing effect on stereoselection of DL-alanine-N-carboxyanhydride oligomerization in dioxane solution.

The possibility of stereoselection through the DL-alanine-N-carboxyanhydride (NCA-DL-Ala) oligomerization, and the effect of freezing on it have been investigated. To this end, the chirality of peptides obtained by oligomerization for 1 and 3 days, respectively, in liquid (+22 degree celsius) and frozen (-18 degree celsius) dioxane solutions, was analyzed. These water-soluble samples were fractionated by gel filtration, aliquots of the fractions were completely hydrolyzed and then derivatized with Marfey reagent (1-fluoro-2,4-dinitrophenyl-5-L-alanine amide).

Chemotactic activity of oligopeptides containing an EWS motif on Tetrahymena pyriformis: the effect of amidation of the C-terminal residue.

Chemotactic properties of 3-7-mer peptides containing an EWS motive and their peptide amides synthesized and characterized by us were investigated in Tetrahymena pyriformis GL model. Analysis of the peptide acids shows that SEWS possesses exceptionally strong (660%+/-21; 430%+/-18) chemoattractant ability at 10(-12) and 10(-11) m respectively. The shorter peptide (EWS) possesses chemorepellent activity, while longer peptides display neutral (WSEWS) or moderate chemoattractant (EWSEWS and GEWSEWS) chemotactic ability.

9alpha,20-Dihydroxyecdysone, a new natural ecdysteroid from Silene italica ssp. nemoralis.

A new natural compound, 9alpha,20-dihydroxyecdysone (1), and two known related compounds, 20-hydroxyecdysone and ecdysone, were isolated from the herb Silene italica ssp. nemoralis. Compound 1 is the first C-9 hydroxylated ecdysteroid with a cis-fused A/B ring junction to have been isolated from a plant source, and its structure was determined using a combination of spectroscopic techniques.

Mass spectrometric and chemical stability of the Asp-Pro bond in herpes simplex virus epitope peptides compared with X-Pro bonds of related sequences.

The mass spectrometric analysis of the immunodominant epitope region (273-284) of herpes simplex virus type 1 (HSV-1) glycoprotein D (gD) showed a favoured fission at the Asp-Pro peptide bond. The fast atom bombardment collision induced dissociation (FAB-CID) study of closely related X-Pro peptides documented that neither the length nor the amino acid composition of the peptide has a significant influence on this preferential cleavage. At the same time the DP bond proved to be sensitive to acidic conditions in the course of peptide synthesis.