To study the EcoB restriction DNase/ATPase and modification methylast to (i) understand how it can be broken nonspecifically, yet receive only a defined number of breaks; (ii) understand the role of each subunit of the enzyme in the reaction; (iii) determine the structure of the 3'- and 5'-terminal formed by the DNase, and of the recognitio site of the enzymes; (iv) understand the significance of the EcoB restriction ATPase; (v) understand the relationship to and interactions with other host and virus metabolic functions; (vi) understand the mechanism by which the enzyme "travels" along DNA. To study the reaction of the recBC DNase/ATPase by electron microscopy to learn about its role in DNA recombination. To study the ATPase-mediated melting reaction biochemically. To study the specificity and significance of E.Coli endonucleases III and V.