tailieunhanh - Báo cáo khoa học: Differential susceptibility of Plasmodium falciparum versus yeast and mammalian enolases to dissociation into active monomers

In the past, several unsuccessful attempts have been made to dissociate homodimeric enolases into their active monomeric forms. The main objective of these studies had been to understand whether intersubunit interactions are essential for the catalytic and structural stability of enolases. | ễFEBS Journal Differential susceptibility of Plasmodium falciparum versus yeast and mammalian enolases to dissociation into active monomers Ipsita Pal-Bhowmick Sadagopan Krishnan and Gotam K. Jarori Department of BiologicalSciences Tata Institute of FundamentalResearch Colaba Mumbai India Keywords enolase monomers Plasmodium falciparum rabbit muscle yeast Correspondence G. K. Jarori Department of Biological Sciences TIFR Homi Bhabha Road Colaba Mumbai 400 005 India Fax 91 22 22804610 Tel 91 22 22782000 E-mail gkj@ Received 7 December 2006 revised 16 January 2007 accepted 12 February 2007 doi In the past several unsuccessful attempts have been made to dissociate homodimeric enolases into their active monomeric forms. The main objective of these studies had been to understand whether intersubunit interactions are essential for the catalytic and structural stability of enolases. Further motivation to investigate the properties of monomeric enolase has arisen from several recent reports on the involvement of enolase in diverse non-glycolytic moonlighting functions where it may occur in monomeric form. Here we report successful dissociation of dimeric enolases from Plasmodium falciparum yeast and rabbit muscle into active and isolatable monomers. Dimeric enolases could be dissociated into monomers by high concentrations 250 mm of imidazole and or hydrogen ions. Two forms were separated using Superdex-75 gel filtration chromatography. A detailed comparison of the kinetic and structural properties of monomeric and dimeric forms of recombinant P. falciparum enolase showed differences in specific activity salt-induced inhibition and inactivation thermal stability etc. Furthermore we found that enolases from the three species differ in their dimer dissociation profiles. Specifically on challenge with imidazole Mg II protected the enolases of yeast and rabbit muscle but not of P. falciparum from dissociation. The observed .