title: Serine hydroxymethyl transferase from Streptococcus thermophilus and L-threonine aldolase from Escherichia coli as stereocomplementary biocatalysts for the synthesis of beta-hydroxy-alpha,omega-diamino acid derivatives.
abstract: A novel serine hydroxymethyl transferase from Streptococcus thermophilus (SHMT) and a L-threonine aldolase from Escherichia coli (LTA) were used as stereocomplementary biocatalysts for the aldol addition of glycine to N-Cbz amino aldehydes and benzyloxyacetaldehyde (Cbz=benzyloxycarbonyl). Both threonine aldolases were classified as low-specific L-allo-threonine aldolases, and by manipulating reaction parameters, such as temperature, glycine concentration, and reaction media, SHMT yielded exclusively L-erythro diastereomers in 34-60 % conversion, whereas LTA gave L-threo diastereomers in 30:70 to 16:84 diastereomeric ratios and with 40-68 % conversion to product. SHMT is among the most stereoselective L-threonine aldolases described. This is due, among other things, to its activity-temperature dependence: at 4 degrees C SHMT has high synthetic activity but negligible retroaldol activity on L-threonine. Thus, the kinetic L-erythro isomer was largely favored and the reactions were virtually irreversible, highly stereoselective, and in turn, gave excellent conversion. It was also found that treatment of the prepared N-Cbz-gamma-amino-beta-hydroxy-alpha-amino acid derivatives with potassium hydroxide (1 m) resulted in the spontaneous formation of 2-oxazolidinone derivatives of the beta-hydroxyl and gamma-amino groups in quantitative yield. This reaction might be useful for further chemical manipulations of the products.
authors.affiliation: Biotransformation group. Instituto de Investigaciones Químicas y Ambientales de Barcelona-CSIC, Barcelona, Spain.
authors.forename: Mariana L
authors.initials: ML
authors.lastname: Gutierrez
authors.forename: Xavier
authors.initials: X
authors.lastname: Garrabou
authors.forename: Eleonora
authors.initials: E
authors.lastname: Agosta
authors.forename: Stefano
authors.initials: S
authors.lastname: Servi
authors.forename: Teodor
authors.initials: T
authors.lastname: Parella
authors.forename: Jesús
authors.initials: J
authors.lastname: Joglar
authors.forename: Pere
authors.initials: P
authors.lastname: Clapés
mesh_terms: D000599:Amino Acids, Diamino / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D004926:Escherichia coli / Q000201:enzymology*; D012696:Glycine Hydroxymethyltransferase / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism; D048249:Streptococcus thermophilus / Q000201:enzymology*; D013997:Time Factors
chemical_list: D000599:Amino Acids, Diamino; D012696:Glycine Hydroxymethyltransferase