MBB 501 PLANT BIOTECHNOLOGY INFORMATION ABOUT DIFFERENT DNA MODIFYING ENZYMES WHAT IS AN ENZYME? Alkaline Phosphatase Polynucleotide kinase Terminal deoxyneucleotidyl transferase Nucleases Exonuclease Bal31 Exonuclease III Endonuclease S1 endonulease Deoxyribonuclease 1 (Dnase 1) RNase A RNase H Restriction Endonuclease PvuI PvuII Different types of endonuclease enzymes The recognition sequences for some of the most frequently used restriction endonucleases. Categorization of enzymes Isoschizomers Neoschizomers Isocaudomers

1. An Assignment on
DNA modifying enzymes
Name : Bhumi A. Gameti
M.Sc. Agri. GPB 3rd sem
Reg. No.: 04-AGRMA-01998-2019
Submitted to:
Dr. H. N. Zala
Assistant professor,
Dept. of Genetics & Plant Breeding,
C. P. College of Agriculture, S.D.A.U., S. K. Nagar

2. WHAT IS AN ENZYME?
• Enzymes are proteins and certain class of RNA
(ribozymes) which enhance the rate of a
thermodynamically feasible reaction and are not
permanently altered in the process.

3. DNA MODIFYING ENZYMES
• There are numerous enzymes that modify DNA
molecules by addition or removal of specific chemical
groups.

4. A). Alkaline Phosphatase
• This enzyme removes phosphate group at the 5’
terminus of a DNA molecule.

5. B). Polynucleotide kinase
• This enzyme add phosphate group at the 5’ terminus
of a DNA molecule.

6. C). Terminal deoxyneucleotidyl transferase
• This enzyme add one or more deoxyribose
neucleotides at the 3’ terminus of a DNA molecule.

7. Nucleases
• Nucleases are enzymes that cut, shorten or degrade
nucleic acid molecules.
• There are two types of nucleases enzyme:
1. Exonuclease
2. Endonuclease

8. 1). Exonuclease
• It is able to
break
phosphodiester
bond at the
terminal end of
the DNA
molecule.

9. Examples of Exonuclease
Bal31
• It removes nucleotides from
both the sides of the double
stranded DNA.
• It is purified from the
bacterium Alteromonas
espenjiana.

10. Exonuclease III
• It degrades just one strand
of double stranded DNA
molecule and leave single
stranded DNA as the
product.

11. 2). Endonuclease
• It is able to
break internal
phosphodiester
bond of the
DNA molecule.

12. S1 endonulease
• It cleaves only single strand.
• It is purified from the fungus Aspergillus oryzae

13. Deoxyribonuclease 1 (Dnase 1)
• It cleaves both single stranded and double stranded DNA.
• It is purified from cow pancreas.
This enzyme is non-specific.

14. • RNase A : It digests ssRNA at 3’ terminus.
• RNase H : It digests RNA on RNA-DNA heteroduplex.

15. Special class of endonuclease
Restriction Endonuclease
This type of enzymes cleaves specific recognition site
on double stranded DNA.

16. PvuI : It cuts DNA only at the hexanucleotide
CGATCG
• This enzyme isolated from Proteus vulgaris
PvuII : It cuts different hexanucleotide CAGCTG
•This enzyme isolated from same bacterium.

17. Different types of endonuclease enzymes

18. The recognition sequences for some of the most frequently used restriction endonucleases.

19. Restriction enzymes recognize a specific sequence of
nucleotides, and produce a double-stranded cut in the
DNA, these cuts are of two types:
1. Blunt ends.
2. Sticky ends

20. 1. Blunt ends
• In dsDNA, cut produce by restriction endonuclease
enzyme in middle and does not remain any terminal
sequence here. This ends are known as blunt ends.

21. 2. Sticky ends
• In dsDNA, cut produce by restriction endonuclease
enzyme on both the srands. Two over hangs (extra
nucleotides are present) will be produce on the both ends.
This ends are known as sticky ends.

22. Categorization of enzymes
• Isoschizomers
Restriction enzymes that recognize the same sequence and produce cut in
same location.
e.g. sph-I & Bbu-I CGATAC/G
• Neoschizomers
Restriction enzymes that recognize the same sequence but produce cut in
different location.
e.g. sma-I [GGG/CCC] & Xma-I [G/GGCCC]
• Isocaudomers
Restriction enzymes that recognize slight different sequence but produce
cut in same location.
e.g. Sau3A & BamHI Both gives GATC sticky ends.

23. THANK YOU..