00389nam a2200121Ia 4500008004100000022001400041040001100055100002700066245008400093260006300177300001700240300001000257251112s9999||||xx |||||||||||||| ||und||  a0027-8424  aCNCLSA  aNicholas R. Cozzarelli 0aProceedings of the National Academy Of Sciences of the United States of America  cJune 8, 1999bThe National Academy of SciencesaWashington  aP. 6575-7610  bV. 96