Esterase Activity of Proteases
Numerous highly selective ester hydrolyses catalyzed by α-chymotrypsin [120] and
papain have featured in excellent reviews [273] and the examples shown above
illustrate their synthetic potential. On large scale, subtilisin (a protease which is
widely used in detergent formulations) is a lost cost alternative [274–276].
The major requirements for substrates of type I (see Scheme 2.20) to be
selectively hydrolyzed by proteases, such as α-chymotrypsin, pepsin, papain
and subtilisin are the presence of a polar and a hydrophobic group on the α-center
(R
1 and R
2 , respectively) to mimic the natural substrates – amino acids.
Proteases are also useful for regioselective hydrolytic transformations (Scheme
2.36). For example, while regio-selective hydrolysis of a dehydroglutamate diester
at the 1-position was achieved using α-chymotrypsin, the 5-ester was attacked by
papain [277]. The latter is one of the few enzymes used for organic synthetic
transformations originating from plant sources (papaya). Related protease preparations are derived from fig (ficin) and pineapple stem (bromelain) [278].
In addition to the above mentioned enzymes, two proteases have emerged as
highly selective biocatalysts for hydrolysis. Penicillin acylase is highly
CO 2 H
N
O
F 3 C
O
CO 2 H
Cl
Cl
O
O
CO 2 H
CO 2 H
MeO
COOH
Aryl-O
COOMe
Aryl-O
COOMe
Aryl
COOH
Aryl
COOMe
R
Herbicides:
Anti-inflammatory agents:
Diclofop
Fluazifop
Ibuprofen
Naproxen
S*
* switch in CIP-sequence priority
S*
buffer
R = Aryl-OR = Aryle.e. 87-93%
e.e. 95-100%
Carboxyl
esterase
NP
rac
+
+
R
R
S
S
Scheme 2.35 Resolution of α-substituted propionates by carboxylesterase NP
Cbz
COOH
H
N
COOMe
Cbz
COOMe
H
N
COOH
Cbz
COOMe
H
N
COOMe
buffer
Cbz = Ph-CH 2 -O-COpapain
α-chymotrypsin
1
5
Scheme 2.36 Regio-complementary ester hydrolysis by proteases
70
2 Biocatalytic Applications
Numerous highly selective ester hydrolyses catalyzed by α-chymotrypsin [120] and
papain have featured in excellent reviews [273] and the examples shown above
illustrate their synthetic potential. On large scale, subtilisin (a protease which is
widely used in detergent formulations) is a lost cost alternative [274–276].
The major requirements for substrates of type I (see Scheme 2.20) to be
selectively hydrolyzed by proteases, such as α-chymotrypsin, pepsin, papain
and subtilisin are the presence of a polar and a hydrophobic group on the α-center
(R
1 and R
2 , respectively) to mimic the natural substrates – amino acids.
Proteases are also useful for regioselective hydrolytic transformations (Scheme
2.36). For example, while regio-selective hydrolysis of a dehydroglutamate diester
at the 1-position was achieved using α-chymotrypsin, the 5-ester was attacked by
papain [277]. The latter is one of the few enzymes used for organic synthetic
transformations originating from plant sources (papaya). Related protease preparations are derived from fig (ficin) and pineapple stem (bromelain) [278].
In addition to the above mentioned enzymes, two proteases have emerged as
highly selective biocatalysts for hydrolysis. Penicillin acylase is highly
CO 2 H
N
O
F 3 C
O
CO 2 H
Cl
Cl
O
O
CO 2 H
CO 2 H
MeO
COOH
Aryl-O
COOMe
Aryl-O
COOMe
Aryl
COOH
Aryl
COOMe
R
Herbicides:
Anti-inflammatory agents:
Diclofop
Fluazifop
Ibuprofen
Naproxen
S*
* switch in CIP-sequence priority
S*
buffer
R = Aryl-OR = Aryle.e. 87-93%
e.e. 95-100%
Carboxyl
esterase
NP
rac
+
+
R
R
S
S
Scheme 2.35 Resolution of α-substituted propionates by carboxylesterase NP
Cbz
COOH
H
N
COOMe
Cbz
COOMe
H
N
COOH
Cbz
COOMe
H
N
COOMe
buffer
Cbz = Ph-CH 2 -O-COpapain
α-chymotrypsin
1
5
Scheme 2.36 Regio-complementary ester hydrolysis by proteases
70
2 Biocatalytic Applications