/Home/rccuser/nuclease syuva

732 views
563 views

Published on

nucleases,types,applications and their role

Published in: Education
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
732
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
39
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

/Home/rccuser/nuclease syuva

  1. 1. NUCLEASES
  2. 2. Nucleases are a class of enzymes called hydrolases that catalyzes the hydrolysis of nucleic acids(DNA,RNA) in all organisms including plants and humans. Nucleases are usually specific in action, ribonucleases acting only upon ribonucleic acids (RNA) and deoxyribonucleases acting only upon deoxyribonucleic acids (DNA). There are two types of nucleases: Endonucleases and exonucleases
  3. 3. Exonucleases degrade nucleic acids from one end of the molecule. They opearate either in 5’  3’ or 3’  5’ direction. Endonucleases degrade nucleic acids at specific internal sites, reducing it to smaller and smaller fragments. Restriction enzyme,a endonuclease due to it’s cleavage at specific nucleotide sequence find so much importance in recombinant DNA technlology.
  4. 4. • Nuclease cleavage sites • (phosphodiester linkage) • Cleavage at bond A generates a 5’- phosphate and a 3’ OH terminus • Cleavage at bond B generates a 3’- phosphate and a 5’- hydroxyl terminus
  5. 5. restriction endonuclease A restriction enzyme (or restriction endonuclease) is an enzyme that cuts double- stranded or single stranded DNA at specific recogonition sequences. These enzymes are found in bacteria. Restriction enzymes are of four types. Type 1and 2 require ATP to hydrolyze DNA. Type 3 is independent of methylated DNA,whereas type 4 targets methylated DNA..
  6. 6. Exonucleases degrade nucleic acids by sequentially removing nucleotides from their ends. Two in common use are snake venom phosphodiesterase and bovine spleen phosphodiesterase. Both enzymes act either on DNA or RNA. But two enzymes have complementary specifities.
  7. 7. Snake venom phosphodiesterase acts by ‘a’ cleavage and starts at the free 3’OH end of the polypeptide chain,liberating nucleoside 5’ monophpsphates
  8. 8. In contrast to snake venom phosphodiesterase,spleen enzyme acts by ‘b’ cleavage and starts at the 5’ end of a nucleic acid releasing 3’nucleoside monophosphates.
  9. 9. Role of nucleases Processes under control of nucleases are protective mechanisms against "foreign" (invading) DNA degradation of host cell DNA after virus infections DNA repair DNA recombination, DNA synthesis DNA packaging in chromosomes and viral compartments, maturation of RNAs or RNA splicing.
  10. 10. THANK YOU
  11. 11. HOW DOES SNAKE VENOM ACT ON HUMAN DNA?

×