Molecular Cloning

Front 1

Restriction Enzymes:
Definition and Characteristics

Back 1

- an enzyme that cuts DNA at specific recognition nucleotide sequences [called restriction sites].
- endonucleases
- specific [i.e cut at specific site]

Front 2

Examples of Restriction Enzymes

Back 2

- EcoRI
- HindIII
- PstI
- PaI

Front 3

Restriction Enzymes: EcoRI

Back 3

- an endonuclease enzyme isolated from strains of E. coli
- is part of the restriction modification system.
- a commonly used restriction enzyme.
- creates sticky ends with 5' end overhangs.

=>The nucleic acid sequence where the enzyme cuts is GAATTC, which is a palindrome as the complementary sequence is CTTAAG.

Front 4

Restriction Enzymes: HindIII

Back 4

- a restriction enzyme isolated from Haemophilus influenzae that cleaves the palindromic DNA sequence AAGCTT in the presence of the cofactor Mg2+ via hydrolysis.

- The cleavage of this sequence between the AA's results in 5' overhangs on the DNA called sticky ends:

5'-A |A G C T T-3'
3'-T T C G A| A-5'

Front 5

Restriction Enzymes: PstI

Back 5

- a restriction enzyme from Providencia stuartii.

- PstI recognition and cut site are as follows:
Cut Site
5'CTGCA IG 3'
3'GI ACGTC 5'