Biocatalytic asymmetric synthesis of unnatural amino acids through the cascade transfer of amino groups from primary amines onto keto acids

Article abstract of DOI:10.1002/cctc.201300571

Flee to the hills: An unfavorable equilibrium in the amino group transfer between amino acids and keto acids catalyzed by α-transaminases was successfully overcome by coupling with a ω-transaminase reaction as an equilibrium shifter, leading to efficient asymmetric synthesis of diverse unnatural amino acids, including L-tert-leucine and D-phenylglycine. Copyright

Full text of DOI:10.1002/cctc.201300571

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DOI: 10.1002/cctc.201300571
Biocatalytic Asymmetric Synthesis of Unnatural Amino
Acids through the Cascade Transfer of Amino Groups from
Primary Amines onto Keto Acids
[
a]
Eul-Soo Park, Joo-Young Dong, and Jong-Shik Shin*
The widespread use of unnatural amino acids as chiral auxilia-
ries and ligands for asymmetric synthesis, as versatile building
blocks for the assembly of combinatorial libraries, and as cru-
cial structural motifs in a diverse range of pharmaceuticals and
agrochemicals has fueled research efforts to develop efficient
of l-tert-leucine and d-phenylglycine, which are valuable build-
ing blocks of pharmaceutical drugs.
[17]
In contrast, a-TAs, such as branched-chain transaminase
(BCTA) and d-amino-acid transaminase (DATA), have displayed
[13a,18]
broad substrate specificity toward a-keto acids,
which is
[
1]
synthetic procedures. Whereas natural amino acids, as native
metabolites, are producible through microbial fermentation,
metabolic redesign to enable the fermentative production of
promising for the synthesis of unnatural amino acids. However,
less attention has been paid to the industrial applications of a-
TAs, because the reaction equilibria of most a-TA reactions are
[
2]
unnatural amino acids remains challenging. Therefore, in ad-
close to unity, owing to structural similarities between the sub-
[
3]
[9c,19]
dition to chemocatalytic methods, various biocatalytic ap-
proaches to afford more-sustainable processes have been de-
strates and the products.
For example, the equilibrium
constant (K ) for transamination between trimethylpyruvic
eq
[
1b,4]
veloped,
including the kinetic resolution of racemic amino-
acid (1h) and l-glutamic acid (l-2j) catalyzed by BCTA was
[
5]
[6]
[20]
acid derivatives by using hydantoinase, acylase and ami-
0.67. Therefore, at least a 28-fold molar excess of compound
[
7]
dase and the asymmetric reductive amination of keto acids
l-2j should be employed to achieve a 95% yield of l-tert-leu-
cine (l-2h), which poses a fundamental obstacle to its practical
synthetic applications. To address the thermodynamic limita-
tions of the a-TA reactions, several attempts have been made
to shift the neutrally positioned equilibrium towards the prod-
ucts by the spontaneous or enzymatic removal of the keto-
[
8]
[9]
by using dehydrogenase and transaminase (TA). Asymmetric
amination is favored over kinetic resolution because it offers
1
00% theoretical yield and no need for the racemization of an
[
10]
unwanted enantiomer. Dehydrogenase exploits NAD(P)H as
an external cofactor, whereas TA adopts pyridoxal 5’-phosphate
[9a–c,19,21]
(PLP) as a prosthetic group to mediate amino-group transfer.
acid product.
However, these methods remained ineffi-
Thus, TA does not require an auxiliary enzyme for cofactor re-
cycling, which renders TAs ideal for industrial process develop-
cient in eliminating the thermodynamic constraints and even
necessitated the adoption of an additional enzyme to suppress
side-product formation, which rendered these previous ap-
proaches suboptimal for industrial frameworks.
[
11]
ment of asymmetric amination reactions.
Recent technical advances in the biocatalytic transamination
reaction have widened the choice of synthetic methods for the
preparation of enantiopure amines and amino acids from achi-
In this study, we aimed at developing a scalable strategy for
the industrial production of unnatural amino acids by bypass-
ing the thermodynamic constraints of the a-TA reactions.
There are myriad cascade biochemical reactions in which an
endergonic step is driven by free-energy release from a highly
[
11–12]
ral carbonyl precursors.
Depending on the position of the
transferrable amino group relative to an intramolecular car-
boxy group, TAs fall into two classes: 1) a-TA, which exclusively
abstracts an a-amino group, and 2) w-TA, which can abstract
an amino group from a non-a position or even from primary
[22]
exergonic reaction, such as ATP hydrolysis. Inspired by this
fact, we envisioned that unfavorable a-TA reactions could be
driven to completion by coupling with an w-TA reaction
(Scheme 1), because w-TA reactions between primary amines
[
13]
amines that do not contain a carboxy group. It has been
demonstrated that w-TA could be used to prepare unnatural
[
14]
[15]
[23]
amino acids, such as l-fluoroalanine and l-homoalanine,
and a-keto acids are known to be energetically favorable.
from their corresponding a-keto acids. However, this strategy
is seriously limited by stringent steric constraints in the active
site of w-TA, which precludes the entry of a-keto acids that
For example, the Keq value for the reaction between pyruvic
acid (1a) and (S)-a-methylbenzylamine ((S)-a-MBA) is reported
[23]
to be 1130. However, a challenging problem facing the im-
plementation of such coupled reactions is whether it is possi-
ble to find a competent amino-acid substrate that is capable
of shuttling between the a-TA and w-TA reactions. A suitable
shuttling substrate should be a reactive amino donor for
a given a-TA and the resulting keto acid should be a reactive
amino acceptor toward an w-TA; thus, recycling of the shut-
tling substrate would be efficient. Disappointingly, compound
l-2j (i.e., a universal amino donor for most a-TAs) cannot fulfill
this requirement because all known w-TAs are not reactive at
all toward a-ketoglutaric acid (1j).
[
16]
contain bulkier substituents than an ethyl group. For exam-
ple, to date, no w-TA is available for the asymmetric syntheses
[
a] E.-S. Park, J.-Y. Dong, Prof. Dr. J.-S. Shin
Department of Biotechnology
Yonsei University
2
62 Seongsanno, Seodaemun-Gu, 120-749 Seoul (South Korea)
Fax: (+82)2-362-7265
E-mail: enzymo@yonsei.ac.kr
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201300571.
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OATA, l-alanine (l-2a) could not serve as a shuttling substrate
because it was a non-reactive amino donor toward BCTA. Con-
versely, we had to rule out the three branched-chain amino
acids (l-2d, l-2 f, and l-2g) because their corresponding keto
acids (1d, 1 f, and 1g) were not reactive toward OATA. Howev-
er, it was encouraging to find that l-homoalanine (l-2b) and
2-oxobutyric acid (1b) showed substantial reactivities toward
BCTA and OATA, respectively. This result enabled us to explore
the feasibility of coupled BCTA/OATA reactions by using com-
pound l-2b as the shuttling substrate, so that the thermody-
namic constraint of the BCTA reaction could be eliminated by
the action of OATA.
To perform the coupled BCTA/OATA reactions, three sub-
strate components were required: 1) an a-keto acid, 2) a pri-
mary amine, and 3) a shuttling substrate (i.e., compound l-
2
2
b). Compared with the first two components, compound l-
b was added to the reaction mixture in a much lower con-
centration because the shuttling substrate was not consumed,
but rather regenerated from the OATA reaction. As a result,
compound l-2b mediated the cascade transfer of an amino
group from the primary amine onto the target keto acid. Be-
cause the BCTA reaction was reversible, the accumulation of
compound 1b allowed a reverse reaction to occur (i.e., transa-
mination between a desired amino-acid product and com-
pound 1b) and, consequently, slowed the net reaction rate.
Therefore, the concentration of compound 1b should be kept
as low as possible to suppress the undesirable reverse reaction.
In contrast, the reverse w-TA reaction between compound l-
Scheme 1. The a-TA reactions were driven to completion by coupling with
an w-TA reaction for the asymmetric synthesis of unnatural a-amino acids.
We set out to examine whether the BCTA reactions, which
are useful for the preparation of various unnatural amino acids
that contain aliphatic side chains, could be coupled with an w-
TA reaction. To that end, we searched for a shuttling substrate
by examining the amino-donor specificity of BCTA from Escher-
ichia coli toward amino acids and the amino-acceptor specifici-
2b and a ketone was negligible because the amino-acceptor
[16]
[16a,24]
ty of S-selective w-TA from Ochrobactrum anthropi (OATA) to-
wards their corresponding keto acids (Table 1). These two TAs
showed opposite trends in relative reactivity with regards to
the bulkiness of the side chain on the substrates, which was
ascribed to the optimized substrate specificity of BCTA for the
bulky side chains of branched-chain amino acids and the
severe steric constraints of OATA, thereby allowing the accom-
modation of substituents up to an ethyl group. Despite the
highest amino-acceptor reactivity of compound 1a towards
reactivities of most ketones are very low.
For example,
OATA only showed 0.20 and 0.05% reactivities with 2-buta-
none and acetophenone, respectively, relative to that of com-
pound 1a (see the Supporting Information, Table S1).
As a proof-of-concept, we monitored the progress of the
cascade reaction to produce compound l-2h from compound
1h (20 mm) by using (S)-a-MBA (30 mm) and compound l-2b
(2 mm, 0.1 equiv relative to compound 1h) as co-substrates
(see the Supporting Information, Figure S1). The Keq value of
the transamination between compounds 1h and l-2b was
[25]
measured to be 0.24,
thus predicting that the maximum
conversion of compound 1h into compound l-2h catalyzed
by BCTA alone was only 7% under the above-specified sub-
strate conditions. However, the unfavorable BCTA reaction
could be driven to completion by simultaneously performing
the w-TA reaction (see the Supporting Information, Fig-
ure S1A), thereby resulting in the stoichiometric conversion of
prochiral 1h into enantiopure l-2h (ee>99%) with 99% con-
version. We found that compound 1b initially accumulated
and then the concentration gradually decreased (see the Sup-
porting Information, Figure S1B). This result was presumably
because the BCTA reaction was faster than the OATA reaction
during the early stage of the reaction under the enzyme con-
Table 1. Dependence of the bulkiness of the R substituent on the relative
reactivity of BCTA toward amino acids and OATA toward keto acids.
[a]
R
Relative reactivity [%]
[
b]
[c]
BCTA
OATA
[
d]
l-2a
l-2b
1a
1b
n.r.
30
100
23
l-2d
l-2 f
l-2g
1d
1 f
87
86
n.r.
n.r.
n.r.
1g
100
À1
centrations (i.e., both 10 UmL ). Indeed, we observed that in-
[a] Relative reactivity represents the initial reaction rate (i.e., conversion
creasing the OATA concentration at the constant BCTA level
<
15%), normalized to that of the most-reactive substrate. [b] Substrates:
l-amino acid (20 mm) and compound 1j (20 mm). [c] Substrates: (S)-a-
MBA (20 mm) and keto acid (20 mm). [d] n.r.=not reactive (i.e., relative
reactivity<1%).
led to a decrease in the initial accumulation of compound 1b
(
see the Supporting Information, Figure S2). The initially accu-
mulated compound 1b was completely converted back into
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compound l-2b at the end of the cascade reaction (see the
Supporting Information, Figure S1B), thus indicating that OATA
indeed served as an “equilibrium shifter”, driving the efficient
recycling of compound l-2b. Taken together with the initial
dosage of compound l-2b relative to compound 1h, the
number of recycles of compound l-2b was 10.
in both cases). Because 0.05 molar equivalents of compound l-
2b relative to the keto-acid substrate were used, the number
of recycles of the shuttling substrate was 20.
To extend this cascade-transfer concept to the production of
unnatural d-amino acids, we explored the feasibility of cou-
pling a DATA reaction with an w-TA. Despite broad substrate
specificity toward a diverse range of d-a-amino acids, the in-
dustrial implementation of DATA reactions has lagged because
of the neutral equilibrium position, just like in the BCTA reac-
tions. For example, the Keq value for transamination between
compound 1j and d-homoalanine (d-2b) for the preparation
Because the cascade amino-group transfer reaction was suc-
cessful, we moved onto investigating the asymmetric synthe-
ses of various unnatural amino acids from 100 mm of the keto-
acid substrates. To this end, isopropylamine (IPA) was chosen
instead of (S)-a-MBA as an amino donor for OATA because IPA
was much cheaper than (S)-a-MBA and its deamination prod-
uct (i.e., acetone) is highly volatile. In addition, OATA has
shown substantial amino-donor reactivity towards IPA (43% re-
[30]
of d-glutamic acid (d-2j) was 0.79.
For the DATA/w-TA coupled reactions, w-TA should possess
R stereoselectivity, thereby enabling the regeneration of the d-
amino-acid substrate that is required for the DATA reaction. Be-
cause IPA is an ideal amino donor for w-TA reactions, we
tested three known R-selective w-TAs, that is, those cloned
[
26]
activity relative to (S)-a-MBA). To determine the enzyme con-
centrations, we performed a series of coupled reactions in
À1
which various enzyme levels, that is, 10–30 UmL BCTA and
À1
[31]
[31]
1
5
–100 UmL OATA, were used with 100 mm compound 1h,
mm compound l-2b, and 150 mm IPA (see the Supporting
from Aspergillus terreus, Aspergillus fumigatus, and Arthro-
[32]
bacter sp. (ARTA), to search for a suitable w-TA that showed
substantial activity towards IPA. Disappointingly, all of these
three wild-type w-TAs showed very little reactivity of IPA (i.e.,
less than 1% reactivity relative to (R)-a-MBA). Therefore, we
chose the variant of ARTA (ARmutTA) that was previously engi-
neered by Savile et al. through the laboratory for amination
Information, Table S2). The highest conversion among the
À1
13 runs was achieved at concentrations of 20 and 50 UmL
for BCTA and OATA, respectively, which led us to use these
enzyme concentrations. As shown in Table 2, unnatural l-a-
[33]
evolution of various bulky ketones by using IPA. Indeed, the
[34]
Table 2. Asymmetric synthesis of unnatural l-a-amino acids from a-keto
reactivity of IPA relative to (R)-a-MBA was 8%.
[
a]
acids by using isopropylamine as an amino donor.
To determine the optimal shuttling substrate, the amino-
donor specificity of DATA from Bacillus sphaericus towards d-
amino acids and the amino-acceptor specificity of ARmutTA to-
wards the corresponding keto acids were examined (Table 3). It
[
b]
Entry
Substrate
t
Conversion
[%]
Product
(ee [%])
[h]
1
2
3
4
5
6
1c
1e
1h
1i
1k
1m
9
9
18
5
12
18
99
97
94
98
95
94
l-2c (>99)
l-2e (>99)
l-2h (>99)
l-2i (>99)
l-2k (>99)
l-2m (>99)
Table 3. Determination of
ARmutTA reactions.
a
shuttling substrate for coupled DATA/
Relative reactivity [%]
Substrate
[
a] Reaction conditions: a-keto acid (100 mm), compound l-2b (5 mm),
À1
À1
Amino
acid
Keto
acid
DATA toward
amino acids
ARmutTA toward
keto acids
IPA (150 mm), PLP (0.5 mm), BCTA (20 UmL ), and OATA (50 UmL ) in
phosphate buffer (50 mm, pH 7). [b] Conversions were based on the con-
sumption of the a-keto-acid substrate.
[
a]
[b]
d-2a
d-2b
d-2d
d-2 f
1a
1b
1d
1 f
100
99
2
100
18
n.r.
n.r.
[
c]
4
amino acids that contained aliphatic side chains (Table 2, en-
tries 1–4 and 6) were prepared with conversions higher than
[
a] Substrates: d-amino acid (20 mm) and compound 1j (20 mm). [b] Sub-
strates: (R)-a-MBA (20 mm) and keto acid (20 mm). [c] n.r.=not reactive
i.e., relative reactivity<1%).
94% within 18 h and excellent enantiopurities. Among these
(
various unnatural amino acids, compound l-2h is an essential
[
17a]
component of HIV-protease inhibitors
and of chiral ligands
[
27]
for asymmetric synthesis, l-norvaline (l-2c) is a key inter-
has been reported that the parental enzyme of ARmutTA does
[
28]
mediate in perindopril (an ACE inhibitor), and l-3-hydroxya-
damantylglycine (l-2m) is a building block of saxagliptin,
which is under development for the treatment of type-2 diabe-
not show any reactivity toward a-keto acids that contain bulki-
[32]
er side chains than an ethyl group, reminiscent of the strong
steric constraints in the active-site pocket of OATA. Despite the
multiple mutations to endow ARmutTA to accept ketones with
[
29]
tes. Owing to the broad substrate specificity of BCTA, the
coupled reaction also enabled the efficient preparation of un-
natural aromatic amino acids, such as l-phenylglycine (l-2k;
Table 2, entry 5). Besides unnatural amino acids, the BCTA/
OATA coupled reaction also enabled the efficient synthesis of
natural branched-chain amino acids under the same conditions
as mentioned above, that is, l-valine (l-2d) and l-leucine (l-
[33]
bulky substituents, ARmutTA was found to retain the steric
constraints in terms of the accommodation of a-keto acids, be-
cause the amino-acceptor reactivities of compounds 1a, 1b,
[32]
1d, and 1 f were similar to those observed with ARTA. Taken
together with the comparable reactivities of compounds d-2a
and d-2b with DATA, compound d-2a was chosen as the shut-
tling amino acid for the coupled DATA/ARmutTA reactions.
2
f) with 92 and 97% conversion, respectively, at 9 h (ee>99%
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We performed the asymmetric synthesis of seven d-amino
acids from prochiral keto acids (100 mm except for compound
enantiopure amino acids, which are required for pharmaceuti-
[38]
cal applications (i.e., >99.5% ee). Despite the remarkable ad-
[3b]
1
l) by using compound d-2a (0.05 mol equiv to the keto acid)
vances in asymmetric Strecker syntheses,
achieving such
and IPA (1.5 equiv) as co-substrates (Table 4). The coupled
a high enantiopurity of the products in a single catalytic step
remains challenging. A typical example of the biocatalytic
asymmetric synthesis of unnatural amino acids is the industrial
preparation of compound l-2h from compound 1h by using
amino-acid dehydrogenase (AADH), coupled with formate de-
Table 4. Coupled DATA/ARmutTA reactions for the preparation of
[
a]
d-a-amino acids.
[6a,39]
[
b]
hydrogenase for cofactor recycling.
The AADH approach
Entry
Substrate
t
Conv.
[%]
Product
(ee [%])
[h]
was also applied to preparation of other unnatural amino
[40]
[41]
acids, such as compounds l-2k and l-2m, which necessi-
tated three substrates and a cofactor (i.e., a target keto acid,
ammonia, formate, and NADH). Although a much-smaller
amount of NADH was required, its compulsory use as an ex-
pensive cofactor often imposed a significant burden in terms
of production costs. In contrast, the TA approach lacks such an
expensive component and instead employs stoichiometric
amounts of the keto acid and IPA, as well as trace amounts of
a shuttling substrate. Another drawback of the AADH ap-
proach is that a d-stereoselective AADH that possesses as
1
2
3
4
5
6
7
1c
1d
1e
1 f
1j
3
7
5
7
5
98
96
96
99
99
97
99
d-2c (>99)
d-2d (>99)
d-2e (>99)
d-2 f (>99)
d-2j (>99)
d-2k (>99)
d-2l (>99)
1k
12
3
[c]
1l
[a] Reaction conditions: a-keto acid (100 mm), compound d-2a (5 mm),
À1
À1
IPA (150 mm), PLP (0.5 mm), DATA (5 UmL ), and ARmutTA (50 UmL ) in
phosphate buffer (50 mm, pH 7). [b] Conversions were based on the con-
sumption of the keto-acid substrate. [c] Concentrations of the three sub-
strate components were halved because the solubility of phenylpyruvic
acid (1l) was lower than 100 mm.
[42]
broad substrate specificity as DATA is not present in nature.
In contrast, DATA is ubiquitous in living organisms and, hence,
is promising for the asymmetric synthesis of a diverse range of
d-amino acids, including compound d-2k, as illustrated herein.
We expect that our approach is generally applicable to other
a-TAs, such as aspartate transaminase and aromatic amino-
acid transaminase, if a suitable shuttling substrate can be
exploited.
DATA/ARmutTA reactions enabled the efficient synthesis of d-
amino acids with >96% conversions and excellent enantiopur-
ities (>99% ee) within 12 h. The resulting d-amino acids in-
clude the essential building blocks of pharmaceutical com-
pounds: d-glutamic acid (d-2j) for spiroglumide (treatment of
[
35]
bowel disorders), d-phenylglycine (d-2k) for ampicillin (anti-
[
17b]
Acknowledgements
biotics),
and d-phenylalanine (d-2l) for nateglinide (antidia-
[
36]
betes). Moreover, d-valine (d-2d) is used for the preparation
[
37]
This work was supported by the Advanced Biomass R&D Center
of fluvalinate (insecticide). Because DATA displays a broad
substrate tolerance, this DATA/ARmutTA strategy provides
a robust synthetic method for the preparation of a diverse
range of d-amino acids.
(
ABC-2010-0029737) through the National Research Foundation
of Korea funded by the Ministry of Education, Science and
Technology.
To demonstrate the scalability of the cascade transfer con-
cept, we performed the preparative-scale syntheses of com-
pounds l-2h and d-2k through BCTA/OATA and DATA/ARmutTA
coupled reactions, respectively, in a 50 mL reaction mixture
that contained the a-keto acid (300 mm), the shuttling amino
Keywords: amino acids · asymmetric synthesis · biocatalysis ·
enzymes · thermodynamics
[1] a) J. S. Ma, Chimica Oggi 2003, 21, 65–68; b) M. Breuer, K. Ditrich, T.
Habicher, B. Hauer, M. Keßeler, R. Stꢁrmer, T. Zelinski, Angew. Chem.
2004, 116, 806–843; Angew. Chem. Int. Ed. 2004, 43, 788–824; c) A.
Schmid, J. S. Dordick, B. Hauer, A. Kiener, M. Wubbolts, B. Witholt,
Nature 2001, 409, 258–268; d) H. E. Schoemaker, D. Mink, M. G. Wub-
bolts, Science 2003, 299, 1694–1697; e) A. M. Rouhi, Chem. Eng. News
À1
acid (20 mm), IPA (450 mm), a-TA (35 UmL ), and w-TA
À1
(
30 UmL ). Conversions of over 97% were attained within
24 h. Purification and structural characterization of the amino-
acid products were performed (see the Supporting Informa-
2
004, 82, 47–62; f) U. T. Bornscheuer, G. W. Huisman, R. J. Kazlauskas, S.
tion), which confirmed the recovery of pure compounds l-2h
Lutz, J. C. Moore, K. Robins, Nature 2012, 485, 185–194.
2] a) W. Leuchtenberger, K. Huthmacher, K. Drauz, Appl. Microbiol. Biotech-
nol. 2005, 69, 1–8; b) T. H. P. Maier, Nat. Biotechnol. 2003, 21, 422–427.
(1.37 g, 70% yield, >99% ee) and d-2k (2.02 g, 89% yield,
[
>
99% ee).
In conclusion, we have developed an industrially scalable
[3] a) L. D. Tran, O. Daugulis, Angew. Chem. 2012, 124, 5278–5281; Angew.
Chem. Int. Ed. 2012, 51, 5188–5191; b) S. J. Zuend, M. P. Coughlin, M. P.
Lalonde, E. N. Jacobsen, Nature 2009, 461, 968–970.
strategy that affords the asymmetric synthesis of a diverse
range of enantiopure unnatural amino acids by using a-TAs.
The thermodynamic constraint of the a-TA reactions, which
has hampered their synthetic applications, could be successful-
ly eliminated by simultaneously performing an energetically fa-
vorable w-TA reaction as an “equilibrium shifter”. This TA ap-
proach is expected to provide a competent alternative to che-
[
4] J. Kamphuis, W. H. Boesten, Q. B. Broxterman, H. F. Hermes, J. A. van
Balken, E. M. Meijer, H. E. Schoemaker, Adv. Biochem. Eng./Biotechnol.
1990, 42, 133–186.
[
5] a) M. A. Wegman, M. H. A. Janssen, F. van Rantwijk, R. A. Sheldon, Adv.
Synth. Catal. 2001, 343, 559–576; b) Y. Ikenaka, H. Nanba, K. Yajima, Y.
Yamada, M. Takano, S. Takahashi, Biosci. Biotechnol. Biochem. 1999, 63,
91–95; c) J. M. Clemente-Jimꢂnez, S. Martꢃnez-Rodrꢃguez, F. Rodrꢃguez-
[
3]
mocatalytic methods, in particular for the preparation of
Vico, F. J. L. Heras-Vꢄzquez, Recent Pat. Biotechnol. 2008, 2, 35–46; d) J.
ꢀ
2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 2013, 5, 3538 – 3542 3541

CHEMCATCHEM
COMMUNICATIONS
www.chemcatchem.org
Altenbuchner, M. Siemann-Herzberg, C. Syldatk, Curr. Opin. Biotechnol.
J. S. Heier, J. D. Rozzel, Biocatalysis, (Ed.: D. A. Abramowicz), Van Nos-
trand Reinhold, New York, 1990, pp. 133–155.
2001, 12, 559–563.
[
6] a) A. S. Bommarius, M. Schwarm, K. Drauz, Chimia 2001, 55, 50–59; b) S.
Yano, H. Haruta, T. Ikeda, T. Kikuchi, M. Murakami, M. Moriguchi, M. Wa-
kayama, J. Chromatogr. B 2011, 879, 3247–3252; c) H. K. Chenault, J.
Dahmer, G. M. Whitesides, J. Am. Chem. Soc. 1989, 111, 6354–6364.
7] a) L. Krieg, M. B. Ansorge-Schumacher, M. R. Kula, Adv. Synth. Catal.
[22] J. M. Berg, J. L. Tymoczko, L. Stryer, Biochemistry, Freeman, New York,
2002, pp. 374–380.
[23] J. S. Shin, B. G. Kim, Biotechnol. Bioeng. 1998, 60, 534–540.
[24] E.-S. Park, M. S. Malik, J.-Y. Dong, J.-S. Shin, ChemCatChem 2013, 5,
1734–1738.
[25] The transamination between compounds 1h (20 mm) and l-2b
(20 mm) was performed by using BCTA. The equilibrium concentrations
of compounds 1h and 1b were determined to be 13.3 and 6.5 mm, re-
spectively, thus leading to Keq =0.24.
[26] The relative reactivity was calculated by comparing the initial reaction
rates with 20 mm 1a and 20 mm (S)-a-MBA or IPA.
[27] a) N. S. Josephsohn, K. W. Kuntz, M. L. Snapper, A. H. Hoveyda, J. Am.
Chem. Soc. 2001, 123, 11594–11599; b) P. Vachal, E. N. Jacobsen, J. Am.
Chem. Soc. 2002, 124, 10012–10014; c) J. Legros, C. Bolm, Angew.
Chem. 2003, 115, 5645–5647; Angew. Chem. Int. Ed. 2003, 42, 5487–
5489.
[
[
2002, 344, 965–973; b) H. Komeda, N. Ishikawa, Y. Asano, J. Mol. Catal.
B 2003, 21, 283–290.
8] a) L. P. B. GonÅalves, O. A. C. Antunes, E. G. Oestreicher, Org. Process Res.
Dev. 2006, 10, 673–677; b) L. P. B. GonÅalves, O. A. C. Antunes, G. F.
Pinto, E. G. Oestreicher, Tetrahedron: Asymmetry 2000, 11, 1465–1468;
c) W. Hummel, M. Kuzu, B. Geueke, Org. Lett. 2003, 5, 3649–3650.
9] a) D. J. Ager, T. Li, D. P. Pantaleone, R. F. Senkpeil, P. P. Taylor, I. G. Fother-
ingham, J. Mol. Catal. B 2001, 11, 199–205; b) T. Li, A. B. Kootstra, I. G.
Fotheringham, Org. Process Res. Dev. 2002, 6, 533–538; c) P. P. Taylor,
D. P. Pantaleone, R. F. Senkpeil, I. G. Fotheringham, Trends Biotechnol.
[
1998, 16, 412–418; d) J. Y. Hwang, J. Park, J. H. Seo, M. Cha, B. K. Cho, J.
Kim, B. G. Kim, Biotechnol. Bioeng. 2009, 102, 1323–1329.
10] N. J. Turner, Curr. Opin. Chem. Biol. 2010, 14, 115–121.
11] a) D. Koszelewski, K. Tauber, K. Faber, W. Kroutil, Trends Biotechnol. 2010,
[28] V. Michel, B. Jean, M. Bernard, R. Georges, US Patent No. 4,902,817,
1990.
[
[
[29] a) D. J. Augeri, J. A. Robl, D. A. Betebenner, D. R. Magnin, A. Khanna,
J. G. Robertson, A. Wang, L. M. Simpkins, P. Taunk, Q. Huang, S.-P. Han,
B. Abboa-Offei, M. Cap, L. Xin, L. Tao, E. Tozzo, G. E. Welzel, D. M. Egan,
J. Marcinkeviciene, S. Y. Chang, S. A. Biller, M. S. Kirby, R. A. Parker, L. G.
Hamann, J. Med. Chem. 2005, 48, 5025–5037; b) S. A. Savage, G. S.
Jones, S. Kolotuchin, S. A. Ramrattan, T. Vu, R. E. Waltermire, Org. Process
Res. Dev. 2009, 13, 1169–1176.
28, 324–332; b) S. Mathew, H. Yun, ACS Catal. 2012, 2, 993–1001; c) M.
Hçhne, U. T. Bornscheuer, ChemCatChem 2009, 1, 42–51; d) M. S. Malik,
E. S. Park, J. S. Shin, Appl. Microbiol. Biotechnol. 2012, 94, 1163–1171;
e) Application of transaminases in organic synthesis. M. Hçhne, U. T.
Bornscheuer in Enzymes in Organic Synthesis (Eds.: O. May, H. Grçger, W.
Drauz), Wiley-VCH, Weinheim, 2012, pp. 779–820.
[12] a) D. Koszelewski, I. Lavandera, D. Clay, G. M. Guebitz, D. Rozzell, W.
[30] The transamination between compounds 1j (20 mm) and d-2b
(
20 mm) was performed by using DATA. The equilibrium concentrations
Kroutil, Angew. Chem. 2008, 120, 9477–9480; Angew. Chem. Int. Ed.
of compounds 1j and 1b were determined to be 10.6 and 9.4 mm, re-
spectively, thus leading to Keq =0.79.
31] M. Hçhne, S. Schatzle, H. Jochens, K. Robins, U. T. Bornscheuer, Nat.
Chem. Biol. 2010, 6, 807–813.
32] A. Iwasaki, K. Matsumoto, J. Hasegawa, Y. Yasohara, Appl. Microbiol. Bio-
technol. 2012, 93, 1563–1573.
33] C. K. Savile, J. M. Janey, E. C. Mundorff, J. C. Moore, S. Tam, W. R. Jarvis,
J. C. Colbeck, A. Krebber, F. J. Fleitz, J. Brands, P. N. Devine, G. W. Huis-
man, G. J. Hughes, Science 2010, 329, 305–309.
2
008, 47, 9337–9340; b) R. L. Hanson, B. L. Davis, Y. Chen, S. L. Gold-
berg, W. L. Parker, T. P. Tully, M. A. Montana, R. N. Patel, Adv. Synth. Catal.
008, 350, 1367–1375; c) M. Hçhne, S. Kꢁhl, K. Robins, U. T. Bornsche-
[
[
[
2
uer, ChemBioChem 2008, 9, 363–365.
[
[
13] a) K. Hirotsu, M. Goto, A. Okamoto, I. Miyahara, Chem. Rec. 2005, 5,
160–172; b) B. Y. Hwang, B. K. Cho, H. Yun, K. Koteshwar, B. G. Kim, J.
Mol. Catal. B 2005, 37, 47–55; c) P. K. Mehta, T. I. Hale, P. Christen, Eur. J.
Biochem. 1993, 214, 549–561.
14] H. S. Bea, S. H. Lee, H. Yun, Biotechnol. Bioprocess Eng. 2011, 16, 291–
[
34] The reaction rates were measured at 20 mm 1a and 20 mm (R)-a-MBA
or IPA.
35] M. J. Berna, J. A. Tapia, V. Sancho, R. T. Jensen, Curr. Opin. Pharmacol.
296.
[
[
15] E. Park, M. Kim, J. S. Shin, Adv. Synth. Catal. 2010, 352, 3391–3398.
16] a) J. S. Shin, B. G. Kim, J. Org. Chem. 2002, 67, 2848–2853; b) E. S. Park,
M. Kim, J. S. Shin, Appl. Microbiol. Biotechnol. 2012, 93, 2425–2435.
17] a) P. Lehr, A. Billich, B. Charpiot, P. Ettmayer, D. Scholz, B. Rosenwirth, H.
Gstach, J. Med. Chem. 1996, 39, 2060–2067; b) A. Bruggink, E. C. Roos,
E. De Vroom, Org. Process Res. Dev. 1998, 2, 128–133.
18] a) S. Kawaguchi, Y. Nobe, J. Yasuoka, T. Wakamiya, S. Kusumoto, S. Kura-
mitsu, J. Biochem. 1997, 122, 55–63; b) H. Kagamiyama, H. Hayashi,
Chem. Rec. 2001, 1, 385–394.
[
2
007, 7, 583–592.
[
[
36] G. Matfin, R. E. Pratley, Ther. Adv. Endocrinol. Metab. 2010, 1, 5–14.
37] S. Martꢃnez-Rodrꢃguez, A. I. Martꢃnez-Gꢅmez, F. Rodrꢃguez-Vico, J. M.
Clemente-Jimꢂnez, F. J. Las Heras-Vꢄzquez, Chem. Biodiversity 2010, 7,
[
[
1531–1548.
[
[
38] A. M. Thayer, Chem. Eng. News 2006, 84, 15–25.
39] U. Kragl, W. Kruse, W. Hummel, C. Wandrey, Biotechnol. Bioeng. 1996, 52,
3
09–319.
40] V. Resch, W. M. F. Fabian, W. Kroutil, Adv. Synth. Catal. 2010, 352, 993–
97.
[
19] D. J. Ager, I. G. Fotheringham, Curr. Opin. Drug Discovery Dev. 2001, 4,
[
[
800–807.
9
[
20] The transamination between compounds 1h (20 mm) and l-2j (20 mm)
was performed by using BCTA. The equilibrium concentrations of com-
pounds l-2j and l-2h were determined to be 11 and 9 mm, respective-
ly, thus leading to Keq =0.67.
41] R. L. Hanson, S. L. Goldberg, D. B. Brzozowski, T. P. Tully, D. Cazzulino,
W. L. Parker, O. K. Lyngberg, T. C. Vu, M. K. Wong, R. N. Patel, Adv. Synth.
Catal. 2007, 349, 1369–1378.
42] K. Vedha-Peters, M. Gunawardana, J. D. Rozzell, S. J. Novick, J. Am.
Chem. Soc. 2006, 128, 10923–10929.
[
[
21] a) B. K. Cho, H. J. Cho, S. H. Park, H. Yun, B. G. Kim, Biotechnol. Bioeng.
2003, 81, 783–789; b) V. Hꢂlaine, J. Rossi, T. Gefflaut, S. Alaux, J. Bolte,
Adv. Synth. Catal. 2001, 343, 692–697; c) M. Xian, S. Alaux, E. Sagot, T.
Gefflaut, J. Org. Chem. 2007, 72, 7560–7566; d) K. Bartsch, R. Schneider,
A. Schulz, Appl. Environ. Microbiol. 1996, 62, 3794–3799; e) S. P. Crump,
Received: July 15, 2013
Published online on September 9, 2013
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2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 2013, 5, 3538 – 3542 3542