Total Synthesis of Motuporin and 5-[l-Ala]-Motuporin
摘要:
Total synthesis of the cyclic peptide hepatotoxin motuporin is described, including an efficient synthesis of the constituent amino acid Adda. Three strategies to motuporin are outlined with their relative strengths and weaknesses. Cyclization of the linear peptide precursor was found to proceed moderately well for peptides containing the N-methyldehydrobutyrine residue masked as a threonine, but significant C-terminal epimerization occurred in the presence of the dehydroamino acid. Replacement of the N-methyldehydrobutyrine residue by L-alanine was explored to assess the contribution of this dehydroamino acid to the biochemical activity of motuporin. Some epimerization also was observed during cyclization of the alanine-containing peptide. Synthetic motuporin and both isomers of 5-[L-Ala]-motuporin inhibit the activity of protein phosphatase-l (PP1) in rat adipocyte lysates with comparable IC50 values. These results indicate that the N-methyldehydrobutyrine residue is not essential for PP1 inhibition.
Total Synthesis of the Serine-Threonine Phosphatase Inhibitor Microcystin-LA
作者:John M. Humphrey、James B. Aggen、A. Richard Chamberlin
DOI:10.1021/ja961683e
日期:1996.1.1
element of the cell. There is a diverse group of toxic natural products that inhibit certain phosphatases, thereby disrupting normal biochemical pathways. These toxins can be useful for dissecting the individual biochemical pathways associated with each of these enzymes. This Article describes the first total synthesis of one such toxin, the cyclic heptapeptide microcystin-LA. The synthesis features a convergent