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TK1656, a thermostable l-asparaginase from Thermococcus kodakaraensis, exhibiting highest ever reported enzyme activity

Paper ID Volume ID Publish Year Pages File Format Full-Text
20657 43185 2013 6 PDF Available
Title
TK1656, a thermostable l-asparaginase from Thermococcus kodakaraensis, exhibiting highest ever reported enzyme activity
Abstract

Two l-asparaginase homologs, TK1656 and TK2246, have been found in the genome of Thermococcus kodakaraensis. The gene encoding TK1656 consists of 984 nucleotides corresponding to a polypeptide of 328 amino acids. To examine the properties of TK1656, the structural gene was cloned, expressed in Escherichia coli and the purified gene product was characterized. TK1656 exhibited high asparaginase activity (2350 U mg−1) but no glutaminase activity. The enzyme also displayed the d-asparaginase activity but 50% to that of l-asparaginase. The highest activity was observed at 85°C and pH 9.5. TK1656 catalyzed the conversion of l-asparagine to l-aspartatic acid and ammonia following Michaelis–Menten kinetics with a Km and Vmax values of 5.5 mM and 3300 μmol min−1 mg−1, respectively. The activation energy from the linear Arrhenius plot was found to be 58 kJ mol−1. Unfolding studies suggested that urea could not induce complete unfolding and inactivation of TK1656 even at a concentration 8 M; however, in the presence of 4 M guanidine hydrochloride enzyme structure was unfolded with complete loss of enzyme activity.

Keywords
Thermococcus kodakaraensis; l-Asparaginase; Structural stability; Thermal stability; Unfolding
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TK1656, a thermostable l-asparaginase from Thermococcus kodakaraensis, exhibiting highest ever reported enzyme activity
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Bioscience and Bioengineering - Volume 116, Issue 4, October 2013, Pages 438–443
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us