Pharmaceutical chemistry for MPHIL

2. Presented By
Aqeela Raza
M.Phil. pharmaceutical
chemistry
University of Lahore

3. Restriction
endonuclease

5. INTRODUCTION
• Restriction endonucleases are bacterial
enzymes that, as the name implies, cleave
internal phosphodiester bonds of a DNA
molecule.
• Found naturally in a wide variety of
prokaryotes
• An important tool for manipulating DNA.

7. WHERE DO
RESTRICTION ENZYMES
COME FROM?
•Restriction enzymes are found in
bacteria.
•Bacteria use restriction enzymes to
kill viruses – the enzymes attack
the viral DNA and break it into
useless fragments.

8. ENDS OF RESTRİCTİON FRAGMENTS
Blunt ends
Sticky ends

9. BLUNT ENDS
• Some restriction enzymes cut DNA at
opposite base
• They leave blunt ended DNA fragments
• These blunt ended fragments can be
joined to any other DNA fragment with
blunt ends.
• Enzymes useful for certain types of
DNA cloning experiments

10. STICKY ENDS
•Most restriction enzymes make
staggered cuts
•Staggered cuts produce single
stranded “sticky-ends”

12. MECHANISM OF ACTION
•Restriction Endonuclease scan the
length of the DNA , binds to the DNA
molecule
•when it recognizes a specific sequence
and makes one cut in each of the
sugar phosphate backbones of the
double helix – by hydrolyzing the
phosphodiester bond.
• Specifically, the bond between the 3’
O atom and the P atom is broken.

13. • A major protective strategy for the host is to use
restriction endonucleases (restriction enzymes)
to degrade the viral DNA on its introduction into
a cell
• These enzymes recognize particular base
sequences, called recognition sequences or
recognition sites, in their target DNA and cleave
that DNA at defined positions.

14. TYPES

15. WHEN ARE RESTRICTION ENZYMES
USED?
Restriction enzymes are a basic tool for biotechnology
research. They are used for:
•DNA cloning
•DNA fingerprinting
•Recombinant DNA

16. DNA fragments
from different
species can be
ligated to create
Recombinant DNA

17. DNA fragments
from different
species can be
ligated to
create
Recombinant
DNA

18. Restriction
Enzymes can be
used to generate a
restriction map.
This can provide
useful information
in characterizing a
DNA molecule.

19. EXAMPLES
Enzyme Source
EcoRI Escherichia coli
EcoRII Escherichia coli
BamHI
Bacillus
amyloliquefaciens
HindIII
Haemophilus
influenzae