Immobilized horse liver alcohol dehydrogenase as an on-line high-performance liquid chromatographic enzyme reactor for stereoselective synthesis.

Horse liver alcohol dehydrogenase (HLADH) has been non-covalently immobilized on an immobilized artificial membrane (IAM) high-performance liquid chromatography (HPLC) stationary phase. The resulting IAM-HLADH retained the reductive activity of native HLADH as well as the enzyme's enantioselectivity and enantiospecificity. HLADH was also immobilized in an IAM HPLC stationary phase prepacked in a 13 x 4.1 mm ID column to create an immobilized enzyme reactor (HLADH-IMER). The reactor was connected through a switching valve to a column containing a chiral stationary phase (CSP) based upon p-methylphenylcarbamate derivatized cellulose (Chiralcel OJR-CSP). The results from the combined HLADH-IMER/CSP and chromatographic system demonstrate that the enzyme retained its activity and stereoselectivity after immobilization in the column and that the substrate and products from the enzymatic reduction could be transferred to a second column for analytical or preparative separation. The combined HLADH-IMER/CSP system is a prototype for the preparative on-line use of cofactor-dependent enzymes in large-scale chiral syntheses.

Characterization of a potassium channel toxin from the Caribbean Sea anemone Stichodactyla helianthus.

A peptide toxin, ShK, that blocks voltage-dependent potassium channels was isolated from the whole body extract of the Caribbean sea anemone Stichodactyla helianthus. It competes with dendrotoxin I and alpha-dendrotoxin for binding to synaptosomal membranes of rat brain, facilities acetylcholine release at an avian neuromuscular junction and suppresses K+ currents in rat dorsal root ganglion neurones in culture. Its amino acid sequence is R1SCIDTIPKS10RCTAFQCKHS20MKYRLSFCRK30TCGTC35. There is no homology with other K+ channel-blocking peptides, except for BgK from the sea anemone Bunodosoma granulifera. ShK and BgK appear to be in a different structural class from other toxins affecting K+ channels.

Effects of policosanol chronically administered in male monkeys (Macaca arctoides).

Policosanol, administered orally, has shown a cholesterol-lowering effect in different experimental models. Because lipid-lowering therapy is administered chronically, it is necessary to know the effects of these drugs after long-term administration. 18 adult male Macaca arctoides monkeys were used to study the cholesterol-lowering effects and possible toxicity produced by oral administration of policosanol (0.25, 2.5 and 25 mg/kg) for 54 wk. After 8 wk, a significant reduction of serum total cholesterol and low-density lipoprotein cholesterol was observed in policosanol-treated animals when compared with the controls; this effect persisted throughout the study. The animals' behavioural repertoire, physical condition, haematology and blood biochemistry, as well as spermiogram analysis and electrocardiography, were monitored during the study; ophthalmological and pathological anatomy examinations were performed at the end of the administration period. No drug-related toxicity was detected by any examination. The results gave further evidence of the marked and persistent cholesterol-lowering effects of policosanol that had been observed in different experimental models. There was a significant reduction of spontaneous aortic atherosclerotic lesions in treated animals compared with controls. Policosanol (0.25-25 mg/kg) administered orally for 54 wk brought about a persistent reduction in blood cholesterol levels and was very safe and well tolerated during long-term administration.

Un prototipo para la electroforesis de campo pulsante. Estandarización de las condiciones para la resolución de grandes moléculas de ADN / A prototype for the pulse field electrophoresis: condition for the resolution of large DNA molecules

Se desarrolló un prototipo para la electroforesis de campo pulsante en gel de agarosa, que permite separar moléculas de ADN de hasta 2 000 kb. El equipo se fundamenta en la propiedad que tienen las moléculas grandes de ADN, de fraccionarse en geles de agarosa si son sometidas alternadamente a dos campos eléctricos no homogéneos de orientación perpendicular. En los experimentos, los tiempos de pulso fueron 60s, y se estudió la influencia de la fuerza iónica y el tiempo de corrida sobre la resolución de las bandas. El método fue utilizado para obtener el cariotipo electroforético de dos cepas de Saccharomyces cerevisiae. El trabajo describe las distintas partes del equipo, el protocolo electroforético, y la caracterización parcial de algunas bandas mediante hibridización ADN-ADN con sondas específicas para diferentes cromosomas

Un prototipo para la electroforesis de campo pulsante. Estandarización de las condiciones para la resolución de grandes moléculas de ADN / A prototype for the pulse field electrophoresis: condition for the resolution of large DNA molecules

Se desarrolló un prototipo para la electroforesis de campo pulsante en gel de agarosa, que permite separar moléculas de ADN de hasta 2 000 kb. El equipo se fundamenta en la propiedad que tienen las moléculas grandes de ADN, de fraccionarse en geles de agarosa si son sometidas alternadamente a dos campos eléctricos no homogéneos de orientación perpendicular. En los experimentos, los tiempos de pulso fueron 60s, y se estudió la influencia de la fuerza iónica y el tiempo de corrida sobre la resolución de las bandas. El método fue utilizado para obtener el cariotipo electroforético de dos cepas de Saccharomyces cerevisiae. El trabajo describe las distintas partes del equipo, el protocolo electroforético, y la caracterización parcial de algunas bandas mediante hibridización ADN-ADN con sondas específicas para diferentes cromosomas