title: Isolation and crystallization of lambda exonuclease.
abstract: lambda Exonuclease is a deoxyribonuclease induced by bacteriophage lambda. Mutations in the structural gene for the protein affect general recombination and indicate a possible function for the enzyme. A large scale isolation procedure was employed to purify enough enzyme from a heat-induced lambda lysogen for X-ray crystallographic analysis. Analytical ultracentrifugation and SDS-polyacrylamide electrophoresis revealed that lambda exonuclease is a tetramer with molecular mass 107,000 Da. Crystallization trials produced morphologically perfect crystals of a size suitable for X-ray diffraction studies. Cubic crystallographic symmetry was indicated by the lack of birefringence when the crystals were inspected with polarized light. X-ray precession photographs indicated that lambda exonuclease crystallizes in a space group of P4(1)32, or its enantiomorph P4(3)32, with 24 tetramers in the unit cell of edge 210 A.
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics; D002482:Cellulose / Q000031:analogs & derivatives; D002848:Chromatography, DEAE-Cellulose; D002852:Chromatography, Ion Exchange; D003460:Crystallization; D004279:DNA, Viral / Q000302:isolation & purification; D004926:Escherichia coli / Q000201:enzymology*; D005090:Exodeoxyribonucleases / Q000302:isolation & purification*; D008970:Molecular Weight; D014764:Viral Proteins; D014961:X-Ray Diffraction
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins; D002482:Cellulose; C008881:phosphocellulose; D005090:Exodeoxyribonucleases; C043586:exo protein, Bacteriophage lambda