Simple enzymatic procedure for L-carnosine synthesis: whole-cell biocatalysis and efficient biocatalyst recycling.
Bottom Line: β-Peptides and their derivates are usually stable to proteolysis and have an increased half-life compared with α-peptides.Long-time as well as biocatalyst recycling experiments indicated a high stability of the developed biocatalyst for at least five repeated batches.Application of the recombinant E. coli in a fed-batch process enabled the accumulation of l-carnosine to a concentration of 3.7 g l(-1).
Affiliation: Laboratory of Chemical Biotechnology, TU Dortmund, 44221 Dortmund, Germany.Show MeSH
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Mentions: The recently identified enzyme class of β‐aminopeptidases (Geueke et al., 2005; 2006) catalyses the hydrolysis of unnatural β‐ and mixed β,α‐peptides (Heck et al., 2006) and also the reverse synthesis reaction (Heck et al., 2007). In the present work, we developed a whole‐cell biocatalyst using this new enzymatic activity for the synthesis and production of the β,α‐peptide l‐carnosine as shown in Fig. 2. Here, we showed that harvested cells could be used directly as whole‐cell biocatalysts for the synthesis of l‐carnosine, thereby avoiding time‐ and material‐intensive protein purification. By optimizing the synthesis conditions, we were able to increase the yield of product per β‐alanine‐amide (H‐β‐Ala‐NH2). These conditions enabled the accumulation of high l‐carnosine titres in a fed‐batch process under constant concentrations of H‐β‐Ala‐NH2. Thus, the successful use of this new whole‐cell biocatalyst for l‐carnosine production might present an alternative route to the chemical synthesis procedures (Vinick, 1981; Hanselmann, 2002).
Affiliation: Laboratory of Chemical Biotechnology, TU Dortmund, 44221 Dortmund, Germany.