Introduction to Enzyme and Coenzyme Chemistry - E-Library Home

Enzymatic Hydrolysis and Group Transfer Reactions 105
Arg 166
HN
H 2 N
NH 2
Arg 166
HN
H 2 N
NH 2
17
O 18
O
R
O
P
S
Zn2+
Ser 102
O
H
Zn 2+
R
O
Zn2+
18 O
17 O
O
P
S
Zn 2+
H
Ser 102
Arg 166
HN
H 2 N
NH 2
17 O 18 O
Ser 102
HO
P
O
S
H
Zn2+
Zn 2+
H 2 N Zn2+ Arg 166
HN
Zn 2+
NH2
17 O
18 O
OH
P
S
O
Ser 102
Figure 5.30 Mechanism and stereochemistry of alkaline phosphatase.
(1) Ribonuclease A - cleavage of RNA after pyrimidine (cytidine or uridine)
5'-....X-p-Y-p-C-p-Z-p....-3'
RNase A
5'....X-p-Y-p-C-3' -OPO 3 2 -
+ 5'-HO-Z-p....3'
(2) Restriction endonucleases - cleavage of dsDNA at specific 6-base recognition site
EcoR1 5' N N G A A T T C N N 3'
3' N N C T T A A G N N 5'
BamH1
5' N N G G A T C C N N 3'
3' N N C C T A G G N N 5'
Sma1
5' N N C C C G G G N N 3'
3' N N G G G C C C N N 5'
Figure 5.31 SpeciWcity of phosphodiesterases.