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Tropical Journal of Pharmaceutical Research
Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, Nigeria
ISSN: 1596-5996
EISSN: 1596-9827
Vol. 11, No. 6, 2012, pp. 909-916
Bioline Code: pr12107
Full paper language: English
Document type: Research Article
Document available free of charge

Tropical Journal of Pharmaceutical Research, Vol. 11, No. 6, 2012, pp. 909-916

 en Over-expression of NAD kinase in Corynebacterium crenatum check for this species in other resources and its Impact on L-Arginine Biosynthesis
Rahman, Muhammad Masfiqur; Qin, Zhao Qin; Dou, Wenfang; Zhiming, Rao & Xu, Zhenghong


Purpose: To improve the biosynthesis of L-arginine by overexpressing homologous NAD kinase (ppnk) in Corynebacterium crenatum check for this species in other resources SYPA5-5 and to study its impact in presence of high (HOS) and low oxygen supply (LOS).
Methods: A recombinant plasmid (pJC1-tac-ppnK) harboring homologous NAD kinase (ppnk) was constructed in a shuttle vector pJC1 and transferred in L-arginine producing strain Corynebacterium crenatum SYPA5-5. Furthermore, fermentation was performed by shake flask method with consecutive determination of cell growth and glucose concentration. NAD+ kinase activity was studied by stop method and NADP(H) concentrations were determined by spectrophotometric enzymatic cycling method. To check the biosynthesis of amino acids, HPLC method was used to determine extracellular amino acid concentrations.
Results: In HOS condition, NAD+ kinase activity increased by 116 %, while intracellular concentrations of NADP+ and NADPH increased by 7.3 and 36.8 %, respectively. Whereas, in LOS condition , NAD+ kinase activity increased 49 % , with intracellular 14.67 and 15 % increases in NADP+ and NADPH respectively. More importantly, recombinant strain could produce 26.47 and 11.36 g/L L-arginine in HOS and LOS respectively, which is higher than control strain value of 24.29 and 7.58 g/L respectively.
Conclusion: These results suggest that altering the concentration of co-enzymes by NAD kinase in Corynebacterium crenatum is an effective way to increase NADP+ with concurrent production of NADPH for further enhanced L-arginine biosynthesis in Corynebacterium crenatum in both conditions of high and low oxygen supply.

NAD kinase, PpnK, L-arginine, Corynebacterium crenatum

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