RESUMEN
The glyA gene encoding a serine hydroxymethyl transferase (SHMT) with threonine aldolase activity was isolated from Streptococcus thermophilus YKA-184 chromosomal DNA. This aldolase is a pyridoxal 5'-phosphate-dependent enzyme that stereospecifically catalyzes the interconversion of L-threonine to glycine and acetaldehyde. The enzyme was overexpressed in Escherichia coli M15 as a recombinant protein of 45 kDa with a His6-tag at its N-terminus. The recombinant enzyme was purified to homogeneity by a single chromatographic step using Ni-nitrilotriacetic acid affinity, obtaining a high activity-recovery yield (83%). Lyophilized and precipitated enzymes were stable at least for 10 weeks when stored at -20 degrees C and 4 degrees C. It was observed that the Km for L-allo-threonine was 38-fold higher than that for L-threonine, suggesting this enzyme can be classified as a specific L-allo-threonine aldolase. The optimum pH range of threonine aldolase activity for the recombinant SHMT was pH 6-7. When tested for aldol addition reactions with non-natural aldehydes, such as benzyloxyacetaldehyde and (R)-N-Cbz-alaninal, two possible beta-hydroxy-alpha-amino acid diastereoisomers were produced, but with moderate stereospecificity. The enzyme showed potential as a biocatalyst for the stereoselective synthesis of beta-hydroxy-alpha-amino acids.
Asunto(s)
Glicina Hidroximetiltransferasa/metabolismo , Streptococcus thermophilus/metabolismo , Estabilidad de Enzimas , Escherichia coli/genética , Regulación Enzimológica de la Expresión Génica , Glicina Hidroximetiltransferasa/genética , Proteínas Recombinantes/biosíntesis , Streptococcus thermophilus/enzimología , Streptococcus thermophilus/genéticaRESUMEN
Mushroom poisoning does not occur very often but in autumn the incidence increases. The seriousness of symptoms in some cases justifies the revision of this issue just the event of one family cases occurred recently in our environment. In this paper we are presenting two cases of intoxication by Lepiota bruneoincarnata in two patients of the same family who suffers visceral involvement with a hepatic strike down and death in one of the patients. The rarity, and seriousness of symptoms together with the similarity with intoxication by Amanita phalloides seem very interesting to us to be published.
Asunto(s)
Agaricales , Intoxicación por Setas , Adulto , Resultado Fatal , Femenino , Humanos , Masculino , Persona de Mediana Edad , Intoxicación por Setas/diagnóstico , Intoxicación por Setas/etiología , Intoxicación por Setas/fisiopatologíaRESUMEN
La intoxicación por setas no suele ser habitual, pero es de elevada incidencia en el periodo otoñal y la gravedad de los síntomas, en algunos casos, justifica la revisión del tema, a propósito de un caso familiar acaecido recientemente en nuestro medio.En este artículo presentamos dos casos de intoxicación por Lepiota bruneoincarnata en dos pacientes de la misma familia, que desarrollaron afectación visceral con alteración de la función hepática, con desenlace fatal en uno de ellos.La rareza, gravedad de los síntomas y su semejanza con las intoxicaciones por Amanita phalloides nos ha parecido interesante para su publicación (AU)