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Por favor, use este identificador para citar o enlazar a este item: http://hdl.handle.net/10261/16183

Recombinant production of serine hydroxymethyl transferase from Streptococcus thermophilus and its preliminary evaluation as a biocatalyst

AutorVidal, Luis; Calveras Ibáñez, Jordi; Clapés Saborit, Pere; Ferrer, Pau; Caminal, Glòria
Palabras claveSerine hydroxymethyl transferase
Streptococcus thermophilus
glyA gene
Fecha de publicación23-feb-2005
CitaciónApplied Microbiology and Biotechnology 68(4): 489-497 (2005)
ResumenThe 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°C and 4°C. It was observed that the K m 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 β-hydroxy-α-amino acid diastereoisomers were produced, but with moderate stereospecificity. The enzyme showed potential as a biocatalyst for the stereoselective synthesis of β-hydroxy-α-amino acids.
Descripción9 pages, 3 figures, 3 tables.-- PMID: 15726349 [PubMed].-- Printed version published Sep 2005.
Versión del editorhttp://dx.doi.org/10.1007/s00253-005-1934-1
ISSN0175-7598 (Print)
1432-0614 (Online)
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