{'fraction_non_alphanumeric': 0.019882179675994108, 'fraction_numerical': 0.009572901325478646, 'mean_word_length': 5.350467289719626, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Purification and determination of biological activity of a recombinant enterokinase

Enterokinase is a serine protease in which the light chain containing catalytic domain plays a role for recognition and digestion of a specific peptide of tetra-amino acids. Thus, it has been commonly used in biotechnology to cleave a fusion partner in chimeric protein for releasing target protein. In previous publication, the light chain of enterokinase was expressed in fusion form with thioredoxin to generate chimeric protein Trx-ent. The insoluble Trx-ent was primarily refolded for biological activity of auto-digestion to release enterokinase. In this study, we purified and examined biological activity of light chain recombiant enterokinase. The Trx-ent was refolded in process with denaturation in guanidin and then suitable buffers. Subsequently, the enterokinase was purified by factionation with ethanol precipitation at concentration of 20% to achive purify of 82%. The content of enterokinase obtained was 15.6 mg in 1 liter of fermentation and thus the recovery efficiency reached 8.2%. The activity of the recombinant enterokinase using Trx-FliC fusion protein as substrate was 230 units/µg, equivalent to the enterokinase activity of Invitrogen. This result is potential for application of the recombinant enterokinase in recombinant protein production.