video on YouTube https://www.youtube.com/watch?v=fYCjItN2xPs Is an enzyme that cleaves DNA into fragments at or near specific recognition sites within molecules known as restriction site. Discover in 1970

1. GKM
Restriction Enzyme
Ahmed

2. GKM
Restriction Enzyme
Mechanical Shearing
Random fragments of cutting DNA can be obtained by
By high speed mixing at 1500 rpm
For 30 min
Mechanical Shearing
At 1500 rpm in 30 min
~ 8kbp

3. GKM
Restriction Enzyme
Is an enzyme that cleaves DNA into fragments at or near specific
recognition sites within molecules known as restriction site.
Restriction Enzyme
Discover in 1970
Restriction and Modification System
R & M S

4. GKM
Restriction Enzyme
Naming system of Restriction Enzyme
Genus :
Species :
Strain :
Order discovered :
Example: EcoR1
Escherichia
coli
R
1

5. GKM
Restriction Enzyme
Type of Restriction Enzyme
Type: I
• Multi-subunit proteins
• Function as a single protein complex
• Contain #two R (restriction) subunits
#two M (methylation) subunits
#one S (specificity) subunit
• Required ATP, Mg2+ and S-adenosylmethionine for its Activity
• Cleave DNA at random length from recognition site
Example: EcoB

6. GKM
Restriction Enzyme
Type of Restriction Enzyme
Type: II
• Most common type
• Recognize 4-8 bp sequences
• Required Mg2+ as co-factor
• Cut in close proximity of the recognition site
Example: EcoRI GAATTC
‘5GAATTC3’
‘3CTTAAG5’
‘5G AATTC3’
‘3CTTAA G5’
Palindromic sequence

7. GKM
Restriction Enzyme
Type of Restriction Enzyme
Type: III
• Large enzymes
• Combination restriction and modification
• Cleave outside of their recognition site
• Require two recognition sequence in opposite orientations
within the same DNA molecule
• Required Mg2+ for its Activity
• Example EcoP1

8. GKM
Restriction Enzyme
Isoschizomers Enzyme
They are enzymes that recognize and cut off the same sequence
#Perfect isoschizomers Hind III
Hsv I
A AGCTT
A AGCTT
#Imperfect isoschizomers Sma I CCC GGG
C CCGGGXma I