期刊
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
卷 150, 期 -, 页码 238-246出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.saa.2015.05.061
关键词
Papain; FT-IR; Cold stability; Cold denaturation; Cold inactivation; Aggregation
类别
资金
- Ministry of Education, Science and Technological Development, Republic of Serbia [172049]
Papain is a cysteine protease with wide substrate specificity and many applications. Despite its widespread applications, cold stability of papain has never been studied. Here, we used differential spectroscopy to monitor thermal denaturation process. Papain was the most stabile from 45 degrees C to 60 degrees C with Delta G degrees(321) of 13.9 +/- 0.3 kJ/mol and T-m value of 84 +/- 1 degrees C. After cold storage, papain lost parts of its native secondary structures elements which gave an increase of 40% of intermolecular beta-sheet content (band maximum detected at frequency of 1621 cm(-1) in Fourier transform infrared (FT-IR) spectrum) indicating the presence of secondary structures necessary for aggregation. The presence of protein aggregates after cold storage was also proven by analytical size exclusion chromatography. After six freeze-thaw cycles around 75% of starting enzyme activity of papain was lost due to cold denaturation and aggregation of unfolded protein. Autoproteolysis of papain did not cause significant loss of the protein activity. Upon the cold storage, papain underwent structural rearrangements and aggregation that correspond to other cold denatured proteins, rather than autoproteolysis which could have the commercial importance for the growing polypeptide based industry. (c) 2015 Elsevier B.V. All rights reserved.
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