Reference no: EM132934055

Could you please write and expand the info that I have written below?

Brief History

• Endonuclease enzymes were first observed by two teams of researchers in 1952 -1953.
• Salvador Luria and Mary Human
• Joe Bertani and Jean Weigle
• Their study focused on how bacteria were able to become resistant to bacteriophages.
• Werner Arber was the first to hypothesize how these enzymes work by observing bacteriophage DNA changes.
• His hypothesis consists of 2 statements: 
• Bacteriophage-resistant bacterial cells might express a specific enzyme that degrades only invading bacteriophage DNA, but not their own DNA.
• Bacterial cells might express two types of enzymes: a restriction enzyme and a modification enzyme.
• In 1970, Hamilton Smith was able to verify Arber's hypothesis by successfully purifying and demonstrating an enzyme isolated from H. influenza. He called it "endonuclease R".
• In 1971, Kathleen Danna and Daniel Nathans of Johns Hopkins University demonstrated further activity of Hamilton's enzyme by using the enzyme to produce specific DNA fragments of the Simian virus 40 (SV40).