Restriction enzymes sequenced from fragmentation patterns

A restriction endonuclease cleaves both strands of DNA at a specific nucleotide sequence. A variety of such endonucleases have been obtained from different bacterial species but none so far from higher organisms the number of such purified restriction enzymes already exceeds twenty-five. Each enzyme produces a characteristic fragment pattern from any DNA it digests the number and size distribution of the fragments reflects the frequency and spacing of the restriction sites. 

Finally, as an alternative to the generation of short ladder sequences, captured restriction enzyme fragments could be sequenced from their fragmentation patterns in the mass spectra. This could be accomplished by utilizing delayed extraction to... 

You just isolated a novel recombinant clone and purified the desired insert (a 10,000 bp linear duplex DNA) from the vector. Now you wish to map the recognition sequences for restriction endonucleases A and B. You cleave the DNA with these enzymes and fractionate the digestion products according to size by agarose gel electrophoresis. Comparison of the pattern of DNA fragments with marker DNAs of known sizes yields the following results ... 

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