Esters of proteinogenic amino acids efficiently catalyse the formation of erythrose and threose under aqueous conditions in the highest yields and enantioselectivities yet reported. Remarkably while esters of (L)-proline yield (L)-carbohydrates, esters of (L)-leucine and (L)-alanine generate (D)-carbohydrates, offering the potential to account for the prebiotic link between natural (L)-amino ac...

Tumor-promoting phorbol esters stimulated mouse bone marrow cells to form myeloid colonies in agar cultures without added colony-stimulating factors. The colony-stimulating ability of various phorbol esters correlated well with their ability to promote skin tumors in vivo. These results suggest that phorbol esters mimic the action of specific colony-stimulating factors that regulate growth.

Coupling reactions between benzylamines and boronic esters have been investigated. ortho-Lithiated benzylamines react with boronic esters and a N-activator to afford ortho-substituted benzylic boronic esters with formal 1,1'-benzylidene insertion into the C-B bond. The reaction occurs by a SN2' elimination and 1,2-metalate rearrangement of the N-activated boronate complex to afford a dearomatiz...

Mannich-type reactions of O-Boc glycolic esters across chiral N-sulfinyl-α-chloroaldimines resulted in the efficient and syn-stereoselective synthesis of new γ-chloro-α-hydroxy-β-amino esters (dr > 99 : 1). The α-coordinating ability of the chlorine atom was of great importance for the diastereoselectivity of the Mannich-type reaction and overruled the chelation of the sulfinyl oxygen with the ...

A new method is described for the isolation of nearly pure total cerebrosides from fresh brain. Florisil columns are used to separate the cerebroside hydroxy and normal acids, in the form of their esters, and to separate the saturated and unsaturated esters of each group. The esters within each class are determined by gas chromatography, the hydroxy esters being run as the methyl ethers. Yields...

The ATP-dependent potassium (KATP) channel in the pancreatic beta-cell is a complex of two proteins, the pore-forming Kir6.2 and the sulfonylurea receptor type 1 (SUR1). Both subunits are required for functional KATP channels because expression of Kir6.2 alone does not result in measurable currents. However, truncation of the last 26 or 36 amino acids of the C terminus of Kir6.2 enables functio...

Esters of a hitherto undescribed xanthophyll, now called eschscholtzxanthin, are the principal constituents of the pigment mixture found in the brilliant, golden yellow petals of the California poppy, Eschscholtxia calijornica (l-3) .l Free eschscholtzxanthin, obtained by saponifktion of the esters, has the empirical formula G0H51*~02. The eschscholtzxanthin molecule contains twelve double bond...

The effect of esterification at the 2'-position of desosamine on the antibacterial activity of erythromycin was investigated by determining the bacteriostatic and bactericidal activities of erythromycin and a number of its 2'-esters on S. aureus and relating these activities to the hydrolysis rates of the esters. These studies, together with comparison of the inhibition of protein synthesis in ...

Stimulation of the phosphatidylinositol cycle by neurotransmitters generates diacylglycerol, an activator of protein kinase C, which may regulate some forms of neurotransmission. Phorbol esters, potent inflammatory and tumor-promoting compounds, also activate protein kinase C. We demonstrate potent and selective effects of phorbol esters on smooth muscle, indicating a role for protein kinase C ...

Esters of tetramethylcyclopropanecarboxylic acid (I) with (•})-allethrolonel1), (•}) -pyrethrolone2) and some others3) have activity comparable to that of corresponding esters of natural (+)-transchrysanthemic acid against some insect species. However, these esters show differences in toxicity to mammals which are probably resulted from differences in rates or pathways of metabolism. Therefore,...