Calander Home 2001-2002 2002-2003 March 25 - Mohammad Yousef Arginine kinase structure: Revisiting classical questions in enzymology Date: March 25th Time: Noon to 1 Place: BSBE 6-101 Arginine Kinase (AK) is a member of the guanidino kinase family that plays an important role in buffering ATP concentration in cells with high and fluctuating energy demands. The three-dimensional crystal structure of arginine kinase transition state analog complex has been refined at 1.2 resolution with an overall R-factor of 12.3%. The current model providesa unique opportunity to analyze the structure of a bimolecular (phosphagen kinase) enzyme in its transition state. This atomic resolution structure confirms in-line transfer of the phosphoryl group and the catalytic importance of the precise alignment of the substrates. The structure of the substrate free "open" form has been solved at 2.35 Å and compared to the transition state analogue of the "closed" form. Systematic analysis of the domain movements quantitatively described the structural changes and revealed substrate induced domain motions in AK.