Which was the first restriction endonuclease discovered?

Hind II

The correct answer is Option (3)-Hind II

Restriction enzymes belong to a larger class of enzymes called nucleases. These are of two kinds; exonucleases and endonucleases. Exonucleases remove nucleotides from the ends of the DNA whereas, endonucleases make cuts at specific positions within the DNA.

Today we know more than 900 restriction enzymes that have been isolated from over 230 strains of bacteria each of which recognise different recognition sequences. The first restriction endonuclease is –Hind II. EcoRI and Hind III are also restriction endonuclease .EcoRI comes from Escherichia coli RY 13.

E coli cloning vector pBR 322 has restriction sites (HindIII, EcoRI, BamHl, SaII, PvuII, PstI, ClaI), ori (origin of replication) and antibiotic resistance genes (ampR and tetR).