Novel semisynthetic method for generating full length beta-amyloid peptides.

Bacterial expression of full length beta-amyloid (Abeta) is problematic because of toxicity and poor solubility of the expressed protein, and a strong tendency of Met35 to become oxidized in inclusion bodies. We have developed a semisynthetic method in which Abeta1-29 is expressed in bacteria as part of a fusion protein with a C-terminal intein and Chitin-Binding Domain (CBD). There is also a single residue, N-terminal Met extension.

Ordered nanoclusters in lipid-cholesterol membranes.

X-ray diffraction of sphingomyelin-dihydrocholesterol (SM-DChol) monolayers revealed short-ranged ( approximately 25 A) 2D ordering. These nanoclusters show two distinct regions: below the cusp point of the phase diagram (35 mol% DChol), a constant d spacing was observed; above the cusp, the d spacing increases linearly with DChol in accordance to Vegard's law for binary alloys. The components in this lipidic alloy are thus a 65ratio35 SM-DChol entity and excess DChol.

A catalytic enantioselective hetero Diels-Alder approach to the C20-C32 segment of the phorboxazoles.

[reaction: see text] An efficient synthesis of the C20-C32 segment of the phorboxazoles has been achieved using an enantioselective hetero Diels-Alder reaction catalyzed by Jacobsen's Cr(III) amino indanol Schiff base catalyst.

Synthesis of the C1-C17 segment of phorboxazole B.

The C1-C17 bis-oxane subunit 22 of phorboxazole B is efficiently synthesized by exploiting differential reactivities between similar substituents on the hydropyran rings in 4. Selective dihydroxylation of the equatorial vinyl group, hydroboration of the axial vinyl group, and intramolecular Mitsunobu lactonization serve to fully differentiate the similar hydropyrans.