Pyrroline-5-carboxylate reductase (P5CR) plays an important role in the survival of Mycobacterium tuberculosis and is related to virulence of this pathogen. RT-PCR analysis indicated that proC, encoding P5CR, was expressed at the transcriptional level cultured in vitro. The His-rMtP5CR with an N-terminal His-tag (His-rMtP5CR) was firstly purified in Escherichia coli and rMtP5CR was obtained by removal of the N-terminal fusion partner using enterokinase. His-rMtP5CR had considerable beta-pleated sheet analyzed by circular dichroism spectroscopy. The effect of pit, temperature, cations, denaturants, and detergents on the purified enzyme activity and stability was characterized. The N-terminal fusion partner was Found to have very little effect on the biochemical properties of P5CR. (C) 2005 Elsevier Inc. All rights reserved.