Serine/threonine protein phosphatases and a protein phosphatase 1 inhibitor from Neurospora crassa

The major spontaneously active serine/threonine (Ser/Thr) protein phosphatase activities in N. crassa wild type (FGSC 424) were type 1 (PP1), type-2A (PP2A) and type-2C (PP2C). PP1 and PP2C predominantly dephosphorylated phosphorylase a and casein, respectively. PP2A acted on both substrates, but was two-fold more active against casein. PPI activity was inhibited by protamine, heparin, okadaic acid (IC50 50 nM) and mammalian inhibitor- 1 (lC50 2 nM). On the other hand, PP2A activity was inhibited by much lower concentrations of okadaic acid (IC50 0.2 nM) and also by protamine, but not by heparin or inhibitor-l. About 80 per cent of total PP1 activity was associated with the particulate fraction and could be partially extracted with 0.5 M NaCl. Seventy and ninety percent of PP2A and PP2C activities, respectively, were found in the soluble fraction. In addition we have partially purified an acid and thermostable PP1 inhibitor which effectively inhibits both N. crassa and mammalian PP1.

Acerca de la reactividad de 9*, 11*-epoxidos de la tigogenina con ácido perclórico y yoduro de metil magnesio / About reactivity of 9*, 11*-epoxydes of tigogening with perchloric acid and methyl magnesium iodide

Se estudió la reactividad de la 9*, 11*-epoxitigogenina y su 12 ß-acetato con HCLO4 70 % y CH3MgI. En la reacción catalizada por ácido, la apertura del anillo oxiránico ocurre solamente si está presente el grupo 12 ß-OAc. Cuando se emplea el ataque nucleofílico directo (CH3MgI), la apertura del epóxido no tiene lugar, aun en presencia de este grupo. En este caso, sin embargo, puede ocurrir la apertura del anillo F del sistema espirocetálico

Síntesis de éteres cíclicos prostanoides con actividad hematológica o inmunológica / Synthesis of prostandid cyclic ethers with hematological or inmunological activity

En este trabajo se presenta la síntesis de algunos éteres cíclicos prostanoides, análogos de la prostaciclina obtenidos partiendo del intermediario PGA2 (extraído del coral blando Plexura homomalla, recolectado en la costa note de Venezuela); conjuntamente con algunas pruebas farmacológicas preminares en el área de inmunología o hematología