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Title:
ENZYMATIC METHOD
Document Type and Number:
WIPO Patent Application WO/2015/106922
Kind Code:
A1
Abstract:
The present invention relates to a method comprising the method steps A) Providing at least one compound of the general formula I) where X = divalent organic radical comprising 1 to 19 carbon atoms B) Contacting the compound of the general formula I) with an enzyme E1 selected from the group esterases, lipases and lactonases, characterized in that method step B) is carried out in the presence of at least one aliphatic alcohol comprising 1 to 6 carbon atoms.

Inventors:
ENGEL PHILIP (DE)
HAAS THOMAS (DE)
KROUTIL WOLFGANG (AT)
SATTLER JOHANN H (AT)
Application Number:
PCT/EP2014/078465
Publication Date:
July 23, 2015
Filing Date:
December 18, 2014
Export Citation:
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Assignee:
EVONIK DEGUSSA GMBH (DE)
ENGEL PHILIP (DE)
HAAS THOMAS (DE)
KROUTIL WOLFGANG (AT)
SATTLER JOHANN H (AT)
International Classes:
C12P13/00; C12P7/42
Foreign References:
US20130224807A12013-08-29
Other References:
RAJAGOPALAN ET AL: "Biocatalytic reactions: selected highlights", MATERIALSTODAY, vol. 14, April 2011 (2011-04-01), pages 144 - 152, XP002736931
VAN AS: "Tandem catalysis in polymer chemistry", THESIS (COVER PAGE, CHAPTER 3), 2007, pages 1, 43-74, XP002736932, Retrieved from the Internet [retrieved on 20150306]
SATTLER ET AL: "Introducing an in situ capping strategy in systems biocatalysis to access 6-aminohexanoic acid", ANGEWANDTE CHEMIE INTERNATIONAL EDITION, vol. 53, 3 November 2014 (2014-11-03), pages 14153 - 14157, XP002736933
ESIKOVA ET AL: "Bacteria that degrade low-molecular linear epsilon-caprolactam oligomers", APPLIED BIOCHEMISTRY AND MICROBIOLOGY (MOSCOW), vol. 50, 2014, pages 463 - 470, XP035377922
N.N.: "AMBIOCAS description of main results/foregrounds", PROJECT DESCRIPTION, 2014, pages 1 - 23, XP002736934, Retrieved from the Internet [retrieved on 20150303]
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Claims:
Claims

Method comprising the method steps

A) Providing at least one compound of the general formula I)

where X = divalent organic radical comprising 1 to 19 carbon atoms

B) Contacting the compound of the general formula I) with an enzyme E-i selected from the group

esterases of EC 3.1 , lipases of EC 3.1 .1 and lactonases of EC 3.1 .1 ,

characterized in that method step B) is carried out in the presence of at least one aliphatic alcohol comprising 1 to 6 carbon atoms.

Method according to Claim 1 , characterized in that X is selected from optionally substituted alkylene groups, preferably -(CH2)-, -(CH2)2-, -(CH2)3-, -(CH2)4-, -(CH2)5-, -(CH2)6- and -(CH2)7-, particularly preferably -(CH2)2-, -(CH2)3- and -(CH2)4-.

Method according to Claim 1 or 2, characterized in that the aliphatic alcohol is selected from methanol, ethanol, propanol, isopropanol and butanol, wherein methanol is particularly preferred.

Method according to at least one of the preceding claims, characterized in that the aliphatic alcohol in method step B) is used at a concentration of 5% by weight to 60% by weight, preferably from 10% by weight to 40% by weight, particularly preferably from 12% by weight to 30% by weight, wherein the percentages by weight relate to the total reaction batch.

Method according to at least one of the preceding claims, characterized in that method step B) is carried out in an aqueous environment.

6. Method according to at least one of the preceding claims, characterized in that method step B) is carried out in a temperature range from 5°C to 80°C, preferably from 15°C to 60°C, particularly preferably from 25°C to 40°C. 7. Method according to at least one of the preceding claims, characterized in that method step B) is carried out in a pH range from 3 to 1 1 , preferably from 5 to 9, particularly preferably from 6.5 to 8.

8. Method according to at least one of the preceding claims, characterized in that the

enzyme E-i is selected from the group

XP_003364701.1 (predicted equus caballus carboxylesterase isoform X2),

XP_005608328.1 (predicted equus caballus carboxylesterase isoform X3),

NP_388425.1 (Esterase 008 SD Bacillus subtilis),

Pig Liver Esterase 03 (commercially available from Enzymicals as ECS-PLE03),

Pig Liver Esterase 06 (commercially available from Enzymicals as ECS-PLE06), and also CA081735.1 (Alternative Pig liver esterase),

Gl:576155 (Horse pancreatic lipase Chain A: 1 HPL_A),

Gl:576156 (Horse pancreatic lipase Chain B: 1 HPL_B) and

AAC12774.1 (Esterase from Bacillus subtilis pdb 1 JKM brefeldin A esterase),

and also proteins having a polypeptide sequence in which up to 60% of the amino acid residues are modified compared with the abovementioned reference sequences by deletion, insertion, substitution or a combination thereof.

9. Method according to at least one of the preceding claims, characterized in that, in method step B), at least one enzyme selected from E2, E3 and E4 is used,

wherein the enzyme E2 catalyses the reaction of ω-hydroxycarboxylic esters to give the corresponding co-oxocarboxylic esters,

the enzyme E3 catalyses the reaction of ω-oxocarboxylic esters to give the corresponding ω- aminocarboxylic esters and

the enzyme E4 catalyses the reaction of ω-aminocarboxylic esters to give the corresponding the enzymes co-aminocarboxylic acids.

10. Method according to Claim 9, characterized in that, in method step B), an enzyme combination is used selected from Ε^, E^, EiE4, E1E2E3, EiE3E4, EiE2E4 and

1 1. Method according to Claim 9 or 10, characterized in that E2 is selected from

alkanemonooxygenases, alcohol dehydrogenases and alcohol oxidases.

12. Method according to at least one of Claims 9 to 1 1 , characterized in that E3 is selected from co-transaminases.

13. Method according to at least one of Claims 9 to 12, characterized in that E4 is selected from the group

XP_003364701.1 (predicted equus caballus carboxylesterase isoform X2),

XP_005608328.1 (predicted equus caballus carboxylesterase isoform X3),

NP_388425.1 (Esterase 008 SD Bacillus subtilis),

Pig Liver Esterase 03 (commercially available from Enzymicals as ECS-PLE03),

Pig Liver Esterase 06 (commercially available from Enzymicals as ECS-PLE06), and also

CA081735.1 (Alternative Pig liver esterase),

Gl:576155 (Horse pancreatic lipase Chain A: 1 HPL_A),

Gl:576156 (Horse pancreatic lipase Chain B: 1 HPL_B) and

AAC12774.1 (Esterase from Bacillus subtilis pdb 1 JKM brefeldin A esterase),

and also proteins having a polypeptide sequence in which up to 60% of the amino acid residues are modified in comparison with the abovementioned reference sequences by deletion, insertion, substitution or a combination thereof.

14. Method according to at least one of the abovementioned claims, characterized in that the respective enzymes of the enzyme combinations selected from E-i, E-|E2, E-|E3, E-|E4, EiE2E3, EiE3E4, EiE2E4 and EiE2E3E4 are used in the form of genetically modified cells which have an activity of the abovementioned enzymes which is increased in comparison with the wild type thereof.

Description:
Enzymatic method

Field of the invention The present invention relates to a method comprising the method steps

t least one compound of the general formula I)

where X = divalent organic radical comprising 1 to 19 carbon atoms

B) Contacting the compound of the general formula I) with an enzyme E-i selected from the group

Esterases, lipases and lactonases,

characterized in that method step B) is carried out in the presence of at least one aliphatic alcohol comprising 1 to 6 carbon atoms.

Prior art

Macromolecules, 1995, 28, 73-78, Macromolecules, 2004, 37, 2450-2453 and Macromolecules 2006, 39, 7967-7972 disclose enzymatic methods for hydrolysis of lactones with lipases, esterases and lactonases in non-aqueous media. Under the conditions described, the resultant products polymerize, in such a manner that further modification at the co-position, for example in the form of an amination, is not possible.

The object of the invention was to provide an enzymatically catalyzed method for ring opening of lactones, which makes possible further modification at the co-position.

Description of the invention Surprisingly, it has been found that the method described hereinafter is able to solve the problem posed by the invention. The present invention therefore relates to a method comprising the method steps t least one compound of the general formula I)

where X = divalent organic radical comprising 1 to 19 carbon atoms

B) Contacting the compound of the general formula I) with an enzyme E-i selected from the group

esterases of EC 3.1 , lipases of EC 3.1 .1 and lactonases of EC 3.1 .1 ,

characterized in that method step B) is carried out in the presence of at least one aliphatic alcohol comprising 1 to 6 carbon atoms.

One advantage of the present invention is that the conversion rate of the method is very high.

Therefore, the method can be carried out in a reduced time.

A further advantage of the present invention is that the yields are increased.

A further advantage of the present invention is that the products can be purified in a simplified manner.

A further advantage is that the reaction proceeds highly selectively and no ring opening takes place without conversion to the ester.

The accession numbers listed in connection with the present invention correspond to the protein bank database entries of the NCBI with a date of 01 .10.2013; generally, in the present case, the version number of the entry is identified by ".number" such as, for example, "1 ".

Where documents are cited in the context of the present description, it is intended that their content fully form part of the disclosure content of the present invention.

Unless stated otherwise, all of the stated percentages (%) are percent by mass.

The method according to the invention is suitable, in particular, for producing ω- hydroxycarboxylic esters, wherein the compound of the general formula I) is esterified, with ring opening, with the aliphatic alcohol. In a preferred embodiment of the method according to the invention, X is selected from optionally substituted alkylene groups, preferably -(CH 2 )-, -(CH 2 )2-, -(CH 2 )3-, -(CH 2 )4-, -(CH 2 )5-, -(CH 2 ) 6 - and -(CH 2 ) 7 -, particularly preferably -(CH 2 ) 2 -, -(CH 2 ) 3 - and -(CH 2 ) 4 -. The aliphatic alcohol is preferably selected from methanol, ethanol, propanol, isopropanol and butanol, wherein methanol is particularly preferred.

The aliphatic alcohol in method step B) in particular is used at a concentration of 5% by weight to 60% by weight, preferably from 10% by weight to 40% by weight, particularly preferably from 12% by weight to 30% by weight, wherein the percentages by weight relate to the total reaction batch.

A method preferred according to the invention is characterized in that method step B) is carried out in an aqueous environment. The expression "aqueous environment" is preferably taken to mean that water is used at a concentration of 3% by weight to 95% by weight, preferably from 5% by weight to 90% by weight, particularly preferably from 10% by weight to 85% by weight, wherein the percentages by weight relate to the total reaction batch.

Method step B) of the method according to the invention is preferably carried out in a temperature range from 5°C to 80°C, preferably from 15°C to 60°C, particularly preferably from 25°C to 40°C.

Method step B) of the method according to the invention is preferably carried out in a pH range from 3 to 1 1 , preferably from 5 to 9, particularly preferably from 6.5 to 8.

The "pH" in connection with the present invention is defined as the value which is measured using a calibrated pH electrode as specified in ISO 4319 (1977) for a corresponding

composition at 25°C after stirring for 5 minutes.

Preferably, according to the invention, the enzyme E-i is selected from esterases in which the access tunnel which the substrate must pass along in order to arrive at the active centre is hydrophobic and it is characterized by a hydrophobicity index of 0.1 to 1 .8. The hydrophobicity index is determined as described in Journal of Cheminformatics 2013, 5:39 doi:10.1 186/1758- 2946-5-39 and Protein Eng. (1992) 5 (5): 373-375. doi: 10.1093/protein/5.5.373. According to the invention, preferably, the enzyme E-i is selected from the group XP_003364701.1 (predicted equus caballus carboxylesterase isoform X2),

XP_005608328.1 (predicted equus caballus carboxylesterase isoform X3),

NP_388425.1 (Esterase 008 SD Bacillus subtilis),

Pig Liver Esterase 03 (commercially available from Enzymicals as ECS-PLE03),

Pig Liver Esterase 06 (commercially available from Enzymicals as ECS-PLE06), and also

CA081735.1 (Alternative Pig liver esterase),

Gl:576155 (Horse pancreatic lipase Chain A: 1 HPL_A),

Gl:576156 (Horse pancreatic lipase Chain B: 1 HPL_B) and

AAC12774.1 (Esterase from Bacillus subtilis pdb 1 JKM brefeldin A esterase),

and also proteins having a polypeptide sequence in which up to 60%, preferably up to 25%, particularly preferably up to 15%, in particular up to 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 % of the amino acid residues are modified compared with the abovementioned reference sequences by deletion, insertion, substitution or a combination thereof, and which still possess at least 50%, preferably 65%, particularly preferably 80%, in particular more than 90%, of the activity of the protein having the corresponding abovementioned reference sequence, wherein 100% activity of the reference protein is taken to mean the amount of substance of ε-caprolactone , based on the amount of reference enzyme used that is reacted with methanol to give the corresponding ester per unit time.

A method for determining the activity is described in Example 1 .

It is preferred according to the invention if, in addition to the enzyme E-i in method step B), at least one enzyme selected from E 2 , E 3 and E 4 is used, wherein

the enzyme E 2 catalyses the reaction of ω-hydroxycarboxylic esters to give the corresponding co-oxocarboxylic esters,

the enzyme E 3 catalyses the reaction of ω-oxocarboxylic esters to give the corresponding ω- aminocarboxylic esters and

the enzyme E 4 catalyses the reaction of ω-oxocarboxylic esters to give the corresponding ω- aminocarboxylic acids.

The enzymes E-i, E 2 , E 3 and E 4 can therefore be used as enzyme combinations selected from Ei, E-|E 2 , E1 E3, E1 E4, EiE 2 E 3 , E1 E3E4, EiE 2 E 4 and E 1 E 2 E 3 E 4 .

Depending on the choice of the enzyme combination, the method can be used for producing ω- hydroxycarboxylic esters (e.g. E^, for producing ω-oxocarboxylic esters (e.g. EiE 2 ), for producing ω-aminocarboxylic esters (e.g. E 1 E 2 E 3 ) and/or for producing co-aminocarboxylic acids (e.g. E 1 E 2 E 3 E 4 ).

Methods according to the invention in which in method step B) enzyme combinations comprising E"|E 2 E 3 E 4 are used preferably have the aliphatic alcohol at a concentration of 12% by weight to 22% by weight, wherein the percentages by weight relate to the total reaction batch and particularly preferably, this concentration is combined with a temperature range in method step B) from 25°C to 40°C. Methods preferred according to the invention are characterized in that E 2 is selected from alkane monooxygenases, alcohol dehydrogenases and alcohol oxidases.

Suitable enzymes E 2 are described, for example, as "enzyme E N " in EP2222844 and as

"NAD(P)+-dependent alcohol dehydrogenases" in WO201301 1018.

Preferably according to the invention, the enzyme E 2 is selected from the group P42328.1 (ADH-hT), NP_415995.4 (primary ADH from Escherichia coli), ACB78191 .1 (Ralstonia eutropha), YP_795183.1 (Lactobacillus brevis), ACF95832.1 (Lactobacillus kefiri), ACB78182.1

(Paracoccus pantotrophus), EU427523.1 (Sphingobium yanoikuyae), AY123972.1 (Arthrobacter sp. BP2),

and also

proteins having a polypeptide sequence in which up to 60%, preferably up to 25%, particularly preferably up to 15%, in particular up to 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 % of the amino acid residues are modified in comparison with the abovementioned reference sequences by deletion, insertion, substitution or a combination thereof, and which still possess at least 50%, preferably 65%, particularly preferably 80%, in particular more than 90%, of the activity of the protein having the corresponding abovementioned reference sequence, wherein 100% activity of the reference protein is taken to mean the amount of substance of co-hydroxyhexanoic acid methyl ester based on the amount of reference enzyme used that is reacted to give the corresponding co-oxocarboxylic ester per unit time.

A method for determining the activity is described hereinafter. The activity is determined by photometric measurement of the change in absorption from NAD + to NADH (0.5 mM) at 340 nm in the presence of a substrate (6-hydroxyhexanoic acid methyl ester, 50 mM) and of the suitable enzyme from the group E 2 . Methods preferred according to the invention are characterized in that E 3 is selected from ω- transaminases.

Suitable enzymes E 3 are described, for example, as "enzyme Em" in EP2222844, as

"polypeptide having transaminase activity" in EP2557176 and as "transaminases" in

WO201301 1018.

Preferably according to the invention, the enzyme E 3 is selected from the group NP_901695.1 (Chromobacterium violaceum), YP_917746.1 (Paracoccus denitrificans), and also BAK39753.1 (Arthrobacter sp.), and also the abovementioned suitable enzymes E 3 , and also proteins having a polypeptide sequence in which up to 60%, preferably up to 25%, particularly preferably up to 15%, in particular up to 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 % of the amino acid residues are amended in comparison with the abovementioned reference sequences by deletion, insertion, substitution or a combination thereof and which still possess at least 50%, preferably 65%, particularly preferably 80%, in particular more than 90%, of the activity of the protein having the

corresponding abovementioned reference sequence, wherein 100% activity of the reference protein is taken to mean the amount of substance of ω-oxohexanoic acid methyl ester based on the amount of reference enzyme used reacted to give the corresponding ω-aminocarboxylic ester per unit time.

A method for determining the activity is described hereinafter. The activity of the lyophilised cells (20 mg) is determined using a time-degree of conversion curve, wherein the conversion of the substrate (6-oxohexanoic acid methyl ester, 50 mM) to the amine is determined at various time points (0.5 h, 1 h, 2 h, 4 h, 6 h, 12 h, 20 h). Previously, the rehydration of the cells is performed by shaking (120 rpm, 30 min) with addition of PLP (pyridoxal phosphate) (0.4 μηηοΙ). The NAD + is recycled to NADH (0.5 mM) using a GDH (1 U) and glucose (100 mM). The linear part of the curve is used to calculate the activity.

Preferably according to the invention, the enzyme E 4 is selected from the group

XP_003364701.1 (predicted equus caballus carboxylesterase isoform X2),

XP_005608328.1 (predicted equus caballus carboxylesterase isoform X3),

NP_388425.1 (Esterase 008 SD Bacillus subtilis),

Pig Liver Esterase 03 (commercially available from Enzymicals as ECS-PLE03),

Pig Liver Esterase 06 (commercially available from Enzymicals as ECS-PLE06), and also CA081735.1 (Alternative Pig liver esterase),

Gl:576155 (Horse pancreatic lipase Chain A: 1 HPL_A),

Gl:576156 (Horse pancreatic lipase Chain B: 1 HPL_B) and AAC12774.1 (Esterase from Bacillus subtilis pdb 1JKM brefeldin A esterase), and also proteins having a polypeptide sequence in which up to 60%, preferably up to 25%, particularly preferably up to 15%, in particular up to 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 % of the amino acid residues are modified in comparison with the abovementioned reference sequences by deletion, insertion, substitution or a combination thereof and which still possess at least 50%, preferably 65%, particularly preferably 80%, in particular more than 90%, of the activity of the protein having the corresponding abovementioned reference sequence, wherein 100% activity of the reference protein is taken to mean the amount of substance of co-aminohexanoic acid methyl ester based on the amount of reference enzyme used reacted to give the corresponding ω- aminocarboxylic acid per unit time.

A method for determining the activity is described in Example 1 .

It is possible, and preferred according to the invention, that the enzyme E-i respectively used can perform the enzymatic activity of the enzyme E 4 ; such enzymes are termed above preferred enzymes E-i .

It is preferred according to the invention if, apart from the possible enzyme combinations formed from E-i , E 2 , E 3 and E 4 in method step B), in addition at least one enzyme E 5 selected from alanine dehydrogenases is used.

It is a particular strength of the present invention that this configuration permits a reduction- equivalent-neutral reaction procedure, i.e. the reaction proceeds without supply or removal of electrons in the form of reduction equivalents, since the NAD(P)H generated by the alcohol dehydrogenase in the course of the alcohol oxidation is consumed in the generation of alanine with consumption of an inorganic nitrogen donor, preferably ammonia or an ammonia source. The alanine in turn can be used by the transaminase that is present.

In a preferred embodiment, the term "alanine dehydrogenase", as used herein, is understood as meaning an enzyme which catalyses the conversion of L-alanine with consumption of water and NAD(P) + to pyruvate, ammonia and NAD(P)H. Preferably, the alanine dehydrogenase is an intracellular alanine dehydrogenase.

Preferably, according to the invention, the enzyme E 5 is selected from the group:

Alanine dehydrogenase from Bacillus subtilis (NP_391071 .1 )

Rhizobium leguminosarum (YP_0029754337.1 )

Bacillus megaterium (YP_003565624.1 )

Rhodobacter capsulatus (ADE84249.1 ) ), and also proteins having a polypeptide sequence in which up to 60%, preferably up to 25%, particularly preferably up to 15%, in particular up to 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 % of the amino acid residues in comparison with the abovementioned reference sequences are modified by deletion, insertion, substitution or a combination thereof, and which still possess at least 50%, preferably 65%, particularly preferably 80%, in particular more than 90%, of the activity of the protein having the corresponding abovementioned reference sequence.

Enzyme combinations preferably used in this connection are selected from E 1 E 2 E 5 , E 1 E 2 E 3 E 5 , E 1 E 2 E 4 E 5 , and E 1 E 2 E 3 E 4 E 5 .

It is preferred according to the invention if, in the method according to the invention, the respective enzymes of the possible enzyme combinations are used in the form of genetically modified cells which have an increased activity of the abovementioned enzymes in comparison with the wild type thereof.

The examples listed below illustrate the present invention by way of example, without any intention of restricting the invention, the scope of application of which is apparent from the entirety of the description and the claims, to the embodiments specified in the examples.

Examples:

Example 1: Esterases for ring opening of ε-caprolactone in the presence of methanol Methanol (100 μΙ, 10% v/v) was added to buffer (870 μΙ, 100 mM Na 2 KP0 4 , pH 8.5), together with enzyme (6 mg, rehydrated for 20 min in 30 μΙ buffer).

The reaction was started by adding 6 μΙ (50 μΜ) of ε-caprolactone. After one hour the reaction was stopped by extraction with 600 μΙ of ethyl acetate. After phase separation, the aqueous phase was again extracted with 600 μΙ of ethyl acetate and the two collected organic phases were then combined, dried with Na 2 S0 4 and analysed by GC-MS.

As enzyme, the commercial preparations

Bacillus subtilis "Esterase 008-SD" from Codexis, (NP_388425.1 ) and

"horse liver esterase" were used. In all cases, a conversion to 6-hydroxyhexanoic acid methyl ester was observed.

The "horse liver esterase" used is a mixture of two isoenymes XP_003364701 .1 and

XP_005608328.1 (predicted horse liver esterase), cf. in this context Comp. Biochem. Physiol. D: Genomics Proteomics 2009, 4, 54-65.

Example 2: Combination of esterase with alcohol dehydrogenase and transaminase

L-alanine (250 mM) and NH 4 CI (150 mM) were charged in Eppendorf tubes (2 ml). The pH was adjusted to 8.5 using 6 M NaOH aq. NAD+ (0.5 mg, 0.6 μηιοΙ, in 50 μΙ of H 2 0), the

transaminase co-factor PLP (0.1 mg, 0.4 μηιοΙ, in 50 μΙ of H 2 0) and methanol (100 μΙ, 10% v/v) were added together with 300 μΙ of H 2 0.

Thereafter, the respective enzymes were added in accordance with the table hereinafter. For the ADHs (E 2 ), in the case of ADH-hT (P42328.1 ) 100 μΙ of purified enzyme (0.4 U) were added, alternatively, the 6-hydroxyhexanoate dehydrogenase (chnD) from Arthrobacter sp. BP2 (AY123972.1 ) was used. Of the transaminase (E 3 ), in the case of transaminase, 20 mg of lyophilised cells were added. The two transaminases used are transaminase from Ralstonia eutropha (RalEu) ( YP_917746.1 ) and transaminase from Paracoccus denitrificans

(TA_ParDen) ( YP_917746.1 ). Of the esterase (Ei) from Bacillus subtilis (008) (NP_388425.1 ) and from horse liver (HL) (XP_003364701 .1 and XP_005608328.1 ), 15 μΙ (10 U according to the manufacturer) of the commercially available enzyme were used. The experiment was carried out at 30°C and 120 rpm for 18 h at pH 7.8 - 8.5 (adjusted using 6 M NaOH).

The reaction was started by adding ε-caprolactone (6 μΙ, 50 mM). After 5 min, the pH was increased to 7.5-8.5 by adding NaOH (6 M, 12 μΙ).

The results of the reaction with the described enzyme cascade are summarized in the following table.

No. 6-aminohexanoic acid

[%]

1 a 008 chnD RalEu ~ 7

1 b HL 2

2a 008 hT 2

2b HL 2 3a 008 hT TA_ParDen - 40

3b HL - 75

[al The analysis does not differentiate between 6-aminohexanoic acid and its esters. Example 3: Effect of methanol concentration and temperature

Alanine (250 mM) was charged in an Eppendorf Tube (2 ml). Buffer was added

(Na 2 HP0 4 /KH 2 P0 4 300 mM, pH 8.0, 300 μΙ). NH 4 CI was added (50 μΙ, 267.1 mg dissolved in 1 .25 ml of H 2 0 and supplemented with 20 μΙ of 6 M NaOH aq). NAD+ (0.3 mg, dissolved in 50 μΙ of buffer) and PLP (0.05 mg dissolved in 50 μΙ of buffer; 1 mg/ml of stock solution) were added. The mixtures were shaken up to homogeneous solution at 37°C, 120 rpm, for approximately 10 min.

The effect of the co-solvent methanol was studied on the conversion of ε-caprolactone to 6- aminohexanoic acid. Of the transaminase (TA_ParDen), 20 mg of lyophilised cells were rehydrated for 15 min. Of the ADH-hT, 100 μΙ, equivalent to an activity of 0.4 U on the substrate 6-hydroxyhexanoic acid were used. Of the AlaDH from Bacillus subtilis (NP_388425.1 ) , 10 μΙ having an activity of 0.22 U for alanine as substrate were used. Of the esterase PLE03, 2 mg, equivalent to an activity of 0.66 U, were added.

In addition, NH 4 CI (8 mg, 150 mM), Alanine (22.3 mg, 250 mM), PLP (0.05 mg, 0.18 mM), NAD + (0.5 mg, 0.75 mM) were added. The experimental conditions were 30 °C, 120 rpm, 18 h, pH 7.8 - 8.5 (adjusted using 6M NaOH). The experiment was started by adding the reactant (6 μΙ_ OF ε-caprolactone (50 mM))

The table below shows that with increasing MeOH concentration, formation of 6-aminohexanoic acid is favoured.

MeOH ε-capro- 6-Hydroxyhexanoic 6- v/v lactone acid [%] Aminohexanoic

[%] acid [%]

2 0 78 22

3 0 65 35

5 0 57 43

10 0 49 51 To study the effect of the pH, two different buffer systems were tested similarly to the abovementioned example. The results are summarized in the following table:

Entry MeOH pH buffer ε-Capro- 6- 6-Aminohexanoic v/v (mM) lactone Hydroxyhexanoic acid + ester

[%] acid + ester [%]

[%]

1 2 6.8-7.4 PIPES 0 87 13

(120)

2 5 6.8-7.4 PIPES 0 85 15

(120)

3 10 6.8-7.4 PIPES 0 78 22

(120)

4 15 6.8-7.4 PIPES 0 73 27

(120)

5 2 6.8-7.4 PO 4 (120) 0 86 14

6 5 6.8-7.4 PO 4 (120) 0 80 20

7 10 6.8-7.4 PO 4 (120) 0 71 29

8 15 6.8-7.4 PO 4 (120) 0 65 35

In addition, the effect of temperature was likewise studied using the experimental setup described:

Entry MeOH pH Temp. ε- 6- 6- v/v [°C] capro- hydroxyhexanoic Aminohexanoic

[%] lactone acid + ester acid + ester

[%] [%] [%]

1 20 6.8- 30 0 76 24

7.4

2 25 6.8- 30 16 74 10

7.4

3 10 6.8- 37 0 80 20

7.4

4 15 6.8- 37 2 64 34 20 6.8- 37 13 76

7.4

20 8.7- 30 19 76

9.0

Analogous results using Bacillus subtilis 008 SD as E-i :

Entry MeOH Temp. ε-Capro- 6-Hydroxyhexanoic 6- v/v [°C] lactone acid [%] Aminohexanoic

[%] acid [%]

1 15 30 0 60 40

2 20 30 0 75 25

3 30 30 27 64 9

4 35 30 33 67 0

5 15 37 0 63 37

6 20 37 2 96 2

7 30 37 30 70 0