tailieunhanh - Báo cáo khoa học: The enantioselectivities of the active and allosteric sites of mammalian ribonucleotide reductase

Here we examine the enantioselectivity of the allosteric and substrate bind-ing sites of murine ribonucleotide reductase (mRR). l-ADP binds to the active site andl-ATP binds to both the s- and a-allosteric sites of mR1 with affinities that are only three- to 10-fold weaker than the values for the corresponding d-enantiomers. These results demonstrate the potential of l-nucleotides for interacting with and modulating the activity of mRR, a cancer chemotherapeutic and antiviral target. | iFEBS Journal The enantioselectivities of the active and allosteric sites of mammalian ribonucleotide reductase Jian He1 Beatrice Roy2 Christian Perigaud2 Ossama B. Kashlan3 and Barry S. Cooperman1 1 Department of Chemistry University of Pennsylvania PA USA 2 Laboratoire de Chimie Organique Biomoleculaire de Synthese Universite Montpellier II France 3 Department of Medicine University of Pittsburgh PA USA Keywords allosteric sites enantioselectivity L-ADP l-ATP mammalian ribonucleotide reductase Correspondence B. S. Cooperman Department of Chemistry University of Pennsylvania Philadelphia PA 19104-6323 USA Fax 215 8982037 Tel 215 8986330 E-mail cooprman@ Here we examine the enantioselectivity of the allosteric and substrate binding sites of murine ribonucleotide reductase mRR . L-ADP binds to the active site and L-ATP binds to both the s- and a-allosteric sites of mR1 with affinities that are only three- to 10-fold weaker than the values for the corresponding D-enantiomers. These results demonstrate the potential of L-nucleotides for interacting with and modulating the activity of mRR a cancer chemotherapeutic and antiviral target. On the other hand we detect no substrate activity for L-ADP and no inhibitory activity for N3-L-dUDP demonstrating the greater stereochemical stringency at the active site with respect to catalytic activity. Received 25 October 2004 revised 20 December 2004 accepted 7 January 2005 doi Ribonucleotide reductases RRs EC form a family of allosterically regulated enzymes that catalyze the conversion of ribonucleotides to 2 -deoxy-ribonucleotides and are essential for de novo DNA biosynthesis and repair regulating other enzymes in the DNA synthesis pathway via control of the nucleotide pool 1 . Of the four known classes of RR Ia Ib II and III class Ia which requires two different subunits R1 and R2 for activity and catalyzes the reduction of all four common NDPs is the most widespread .