Expression and purification of glyceraldehyde-3-phosphate dehydrogenase from psychrophilic bacterium

• Main Author: Few Ling, Ling
• Format: Article
• Language: English
• Published: Pusat Pengajian Sains Perubatan Universiti Sains Malaysia 2008
• Subjects: R Medicine (General)
• Online Access: http://eprints.usm.my/50393/1/DR.%20FEW%20LING%20LING%20-%2024%20pages.pdf; http://eprints.usm.my/50393/

Organisms that thrive in cold environments are known as psychrophiles. One of the strategies for their cold adaptation is the ability to synthesize cold-adapted enzymes. Our collection of cold-tolerant microorganisms isolated· from the Antarctic region has offered a potential source for psychrophilic enzymes. Previously our group had successfully cloned the open reading frame for GAPDH gene from an Antarctical bacterium known as phi9. The ORF was cloned into a pET-14b plasmid. The full length GAPDH protein was subsequently expressed in E. coli strain BL21 (DE3), purified as His-tag protein and confirmed to be catalytically active. Results showed that IPTG concentration did not have any effect on protein expression and solubility while 3 hours of induction time at room temperature (28°C) was the best conditions for the expression and solubility of this protein. This protein was shown to be most active at 38°C and its specific activity increased by 40% from 3.6 JlmOI/min/mg to 6.1 J.UllOifmin/mg when the temperature increased from 23°C to 38°C. This work laid the foundation for further biochemical and structural characterizations of GAPDH from a psychrophilic bacterium by providing a highly purified recombinant protein sample.