Peptide synthesis catalyzed by a haloalkaliphilic serine protease from the archaeon Nutrialba magadii

RUIZ, DIEGO M.; IANNUCCI, NANCY BEATRIZ; CASCONE, OSVALDO; DE CASTRO, ROSANA

LETTERS IN APPLIED MICROBIOLOGY

JOHN WILEY & SONS INC

Año: 2010 p. 691 - 696

1472-765X

Aims: Haloarchaeal proteases function optimally in high salt (low water activity);thus, they offer an advantage over the nonhalophilic counterparts as biocatalysts for protease-catalysed peptide synthesis. The haloalkaliphilic archaeon Natrialba magadii secretes a solvent-tolerant protease, Nep (Natrialba magadii extracellular protease). In this work, the ability of Nep to catalyse peptide synthesis was examined. Methods and Results: The tripeptide Ac-Phe-Gly-Phe-NH2 was synthesized using Ac-Phe-OEt and Gly-Phe-NH2 substrates as building blocks in the presenceof Nep, 30% (v ⁄ v) dimethyl sulfoxide (DMSO) and 1Æ5 or 0Æ5 mol l)1 NaCl. Purification and identification of the peptide product was achieved by RP-HPLC and ESI-MS, respectively. The native as well as the recombinant enzyme produced in Haloferax volcanii (HvNep) was similarly effective as catalysts for the synthesis of this model tripeptide with yields of up to 60% and without secondary hydrolysis of the product. HvNep catalysed the synthesis of various tripeptides with preference for those having aromatic amino acids in the P1 site. Conclusion: Nep is able to catalyse peptide synthesis under different salt concentrations in the presence of DMSO. Significance and Impact of Study: The catalytic property of Nep in peptide synthesis combined with overproduction of this protease in Hfx. volcanii anticipates the potential applicability of this haloarchaeal protease in biotechnology.