BamHI is a restriction enzyme

Restriction enzyme

A Restriction Enzyme is an enzyme that cuts double-stranded DNA at specific recognition nucleotide sequences known as restriction sites. Such enzymes, found in bacteria and archaea, are thought to have evolved to provide a defense mechanism against invading viruses...

, derived from Bacillus amyloliquefaciens

Bacillus amyloliquefaciens

Bacillus amyloliquefaciens is a species of bacteria that is the source of the BamH1 restriction enzyme. It also synthesizes a natural antibiotic protein barnase, a widely studied ribonuclease that forms a famously tight complex with its intracellular inhibitor barstar.-Discovery and name:B...

. It has the recognition site (G'GATCC), and leaves a sticky end. One of the earlier enzymes to be used, it is popular for historical reasons, but also because digestion leaves a GATC overhang compatible with many other enzymes. Persistent issues with this specific enzyme spontaneously failing to generate cloneable fragments necessitate aliquoting prior to use. Engineered variants of the enzyme have been created in order to avoid star activity

Star activity

Star activity is a relaxation or alteration of the specificity of restriction enzyme mediated cleavage of DNA that can occur under reaction conditions that differ significantly from those optimum for the enzyme...

.

Recognition site

As at the end of 2010, there were 5 crystal structures of BamH1 in the Protein Data Bank

Protein Data Bank

The Protein Data Bank is a repository for the 3-D structural data of large biological molecules, such as proteins and nucleic acids....