| X-RAY DIFFRACTION |
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301 |
THE ENZYME AND SUBSTRATE WERE MIXED IN EQUIMOLAR AMOUNTS IN A SOLUTION CONTAINING 50 MM MES PH 5.5, 1.5 MM EDTA. THE COMPLEX WAS FORMED BY INCUBATING THE MIXTURE AT 95C FOR 2 MIN., THEN AT 65C FOR 2 MIN., AND FINALLY AT 27C FOR 5 MIN. 1 MM MGCL2 WAS INCLUDED IN THE MIXTURE BEFORE THE FINAL INCUBATION STEP. A 10 MG/ML CONCENTRATION OF RNA WAS USED FOR THE CRYSTALLIZATION EXPERIMENTS. THE RESERVOIR SOLUTION CONTAINED 0.5M (NH4)2SO4, 100 MM MES PH 6.5, AND 35% PEG 3350. AFTER MIXING THE RESERVOIR SOLUTION, THE SALT AND PEG PHASES WERE ALLOWED TO SEPARATE, AND ONLY THE SALT PHASE WAS USED FOR THE DROPS. THE CRYSTALS GREW IN HANGING DROPS OF 2 MICROLITERS AFTER 12 MONTHS OF INCUBATION AT 28C. THE CRYSTALS WERE WASHED IN THE SALT PHASE OF THE RESERVOIR SOLUTION PRIOR TO CRYO-FREEZING. |
