CUT
~
specific sites
restriction enzymes
( endonucleases)
unspecific sites
exonucleases
endonucleases
TRANSFER CHEMICAL GROUPS
~
methyl moieties
methylases
phosphate moieties
kinases
2 Enzymatic Modification of DNA and RNA
25
JO/N
I
cohesive/blunt ends
Iigases
REMOVE
I
phosphate moieties
phosphatases
ADD NUCLEOTIDESIPOL YMERIZE
DNA
~
using a template
DNA-dependent DNA
polymerases
RNA-dependent DNA
polymerases
no template
terminal deoxynucleotidyl transferase
(TdT)
RNA
I
using a template
DNA-dependent RNA
polymerases
Fig. I. Enzyme Classification by Principal Action on DNA/RNA
TYPE/
-specific recognition
sequence
-random cleavage site
-methylation and
cleavage
TYPE II
-specific recognition
sequence
-specific cleavage
site
-no methylation
Fig. 2. Classification of Restrietion Endonucleases
TYPE 111
-specific recognition
sequence
-specific cleavage site
-methylation and
cleavage