Circular β-lactamase: stability enhancement by cyclizing the backbone

摘要: We have cyclized the polypeptide backbone of β-lactamase with a short peptide loop as novel method for protein stabilization, using intein-mediated ligation. Successful cyclization was proven by mass spectrometry and subsequent re-linearization proteolytic cleavage, well resistance against carboxypeptidase. Under conditions experiment, no disulfide bond is present. The circular form found to be significantly more stable irreversible aggregation upon heating than linear form. could purified from one either this heat treatment or his-tag which became exopeptidase-resistant cyclization. increased stability probably due decreased conformational entropy in unfolded state intermediate states. While introduction additional bonds stabilization follows same rationale, strategy may disturb structure less thus constitute general stabilizing those proteins N- C-termini close proximity.