Patent Application
20240401002
The application contains a Sequence Listing which has been submitted electronically in .XML format and is hereby incorporated by reference in its entirety. Said .XML copy, created on Aug. 15, 2024, is named “0283-0524PUS1.xml” and is 39,987 bytes in size. The sequence listing contained in this .XML file is part of the specification and is hereby incorporated by reference herein in its entirety.
The present invention relates to a novel flavin-dependent lactate dehydrogenase (hereinafter referred to as LDH), a nucleic acid encoding the same, a host cell having the nucleic acid, a method for producing LDH including culturing the host cell, and a method for improving stability of lactate dehydrogenase.
Lactic acid concentration in blood and lactic acid concentration in sweat are known as markers that reflect fatigue and physical condition. Lactic acid is a major metabolite and is recognized to be important not only for an index of health management but also health evaluation including in critical ill and/or surgical patients, and lactate levels in body fluids can be an index for various pathological conditions such as circulatory failure, liver disorders, etc. Monitoring of lactate can be used to detect sepsis, hypoxia and the presence of cancerous tissue (Non-Patent Document 1).
In addition, as an enzyme that uses lactic acid as a substrate, FMN-dependent lactate dehydrogenase (hereinafter referred to as FMN-LDH) is known. Saccharomyces cerevisiae-derived FMN-LDH (Non-Patent Document 2) which has heretofore been known has a problem in stability.
As enzymes that use lactic acid as a substrate, lactate oxidase (hereinafter referred to as LOD), NAD-dependent lactate dehydrogenase (hereinafter referred to as NAD-LDH) that uses nicotinamide dinucleotide (NAD) as a coenzyme, and FMN-LDH that uses flavin mononucleotide (FMN) as a coenzyme have been known.
LOD has a problem of producing hydrogen peroxide as a reaction product. In particular, there is a concern that it is undesirable to employ a sensor equipped with an enzyme that can continuously produce hydrogen peroxide, which is a type of reactive oxygen species and a causative substance of oxidative stress, when the lactic acid sensor is used in close contact with the skin or, in some cases, is intended to be implanted subcutaneously. Further, hydrogen peroxide generated by the action of LOD has an adverse effect on the stabilization of LOD itself, and as a means of avoiding a decrease in LOD activity caused by this, a lactic acid sensor in which catalase is coexistent for the purpose of scavenging hydrogen peroxide has been also proposed (Patent Document 1).
NAD-LDH catalyzes an enzymatic reaction that does not produce hydrogen peroxide, so that the problem of forming hydrogen peroxide does not arise. However, in the enzymatic reaction system using NAD-LDH, lactic acid and pyruvic acid react reversibly, so there is a problem that accurate measurement values cannot be obtained for quantitative applications, whereby it is difficult to employ it as a sensor.
FMN-LDH also catalyzes enzymatic reactions that do not produce hydrogen peroxide so the problem of forming hydrogen peroxide does not arise. In addition, there is no problem with reversible reaction, and thus, among the above-mentioned three enzymes, it can be considered to be the most promising as a practical enzyme for the purpose of monitoring lactic acid.
However, Saccharomyces cerevisiae-derived FMN-LDH (Non-Patent Document 2) which has been known as of today has a problem in stability. An object of the present invention is to search for a novel flavin-dependent LDH excellent in stability and to provide a method for improving stability of LDH.
The present inventors searched for a novel flavin-dependent LDH excellent in stability in view of the above-mentioned problems, discovered a mutant LDH improved in stability whereby they have completed the present invention.
The present invention includes the following embodiments.
According to the present invention, a novel flavin-dependent LDH excellent in stability, a nucleic acid encoding the same, a host cell having the nucleic acid, a method for producing LDH including culturing the host cell, and a method for improving stability of LDH can be provided.
Hereinafter, embodiments of the present invention will be explained specifically. Incidentally, the following embodiments are examples of embodying the present invention, and do not limit the present invention within the range.
LDH referred to the present invention is an enzyme that catalyzes the reaction of oxidizing the hydroxyl group of lactic acid to produce pyruvic acid in the presence of an electron acceptor, which is similar to known wild type or mutant type LDH. Incidentally, unless otherwise specifically mentioned, the substrate of LDH is lactic acid, which may be provided as a mixture of L-form and D-form, for example, a racemate, or may be provided as L-form.
The LDH of the present invention may be LDH having an amino acid sequence selected from (i) an amino acid sequence represented by SEQ ID NO: 3, (ii) an amino acid sequence having high identity with the amino acid sequence represented by SEQ ID NO: 3, for example, 70% or more, more preferably 75% or more, further preferably 80% or more, further preferably 85% or more, further preferably 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, further preferably 95% or more, 96% or more, 97% or more, 98% or more, and most preferably 99% or more identity, or (iii) when an alignment with the amino acid sequence represented by SEQ ID NO: 3 is formed, an amino acid sequence having high identity with the amino acid sequence represented by SEQ ID NO: 3 in the region from positions 110 to 502 of SEQ ID NO: 3, for example, 70% or more, more preferably 75% or more, further preferably 80% or more, further preferably 85% or more, further preferably 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, further preferably 95% or more, most preferably 96% or more, 97% or more, 98% or more, and 99% or more identity, and containing deletion of an N-terminus, and/or mutation(s) at one or more positions selected from the group consisting of position 54, position 156, position 349 and position 428. More preferably, the LDH of the present invention has an N-terminus in which it is deleted at positions 2 to 3, positions 2 to 4, positions 2 to 5, positions 2 to 6, positions 2 to 7, positions 2 to 75, positions 2 to 83, or positions 2 to 91 in SEQ ID NO: 3. Also, more preferably, the mutation at position 54 in the LDH having an amino acid sequence represented by SEQ ID NO: 3 of the present invention is A54C, the mutation at position 156 is Y156F, the mutation at position 349 is Y349F, and the mutation at position 428 is F428L.
As a sequence having the amino acid sequence which has high identity with SEQ ID NO: 3 may be those having, for example, the amino acid sequence represented by SEQ ID NO: 5.
The LDH of the present invention may be sufficient with LDH as long as it has an amino acid sequence represented by SEQ ID NO: 5 or has high identity of, for example, 70% or more, more preferably 75% or more, further preferably 80% or more, further preferably 85% or more, further preferably 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, further preferably 95% or more, 96% or more, 97% or more, 98% or more, and most preferably 99% or more, and contains deletion of an N-terminus, and/or mutation(s) at position 52 of SEQ ID NO: 5. More preferably, the LDH of the present invention has an N-terminus in which it is deleted at positions 2 to 3, positions 2 to 4, positions 2 to 5, positions 2 to 6, positions 2 to 7, positions 2 to 73, positions 2 to 81, or positions 2 to 89 in SEQ ID NO: 5. Also, more preferably, the mutation at position 52 (corresponding to position 54 of SEQ ID NO: 3 in alignment with SEQ ID NO: 3) in LDH having the amino acid sequence represented by SEQ ID NO: 5 of the present invention is S52C.
The LDH of the present invention exhibits, as mentioned later, LDH activity only in the amino acid sequence from positions 110 to 502 of the amino acid sequence represented by SEQ ID NO: 3. Accordingly, it can be understood that the amino acid sequence from positions 110 to 502 of the amino acid sequence represented by SEQ ID NO: 3 is a particularly important region for the function (activity) of LDH. The LDH of the present invention may be LDH having an amino acid sequence which has identity of 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, more preferably 95% or more, 96% or more, 97% or more, 98% or more, and 99% or more with the amino acid sequence represented by SEQ ID NO: 3, when an alignment with the amino acid sequence represented by SEQ ID NO: 3 is formed, in the particularly important region (the region corresponding to positions 110 to 502 of SEQ ID NO: 3) for the function (activity) of LDH.
Identity of the amino acid sequence can be calculated by a program such as maximum matching or search homology, etc., of GENETYX Ver. 11 (manufactured by Genetics) or a program such as maximum matching or multiple alignment, etc., of DNASIS Pro (manufactured by Hitachi Solutions).
In order to calculate amino acid sequence identity, by creating an alignment between the LDH represented by SEQ ID NO: 3 and another LDH, a location can be determined the position corresponding to a particular position of the LDH of SEQ ID NO: 3 in another LDH. For example, according to
In one embodiment of the present invention, the present invention is a nucleic acid encoding the above-mentioned LDH.
in one embodiment of the present invention, the present invention is a host cell having the above-mentioned nucleic acid. As the host cell, it is not particularly limited as long as it is a conventional cell used in the field of the art. For example, there may be used Escherichia coli (Escherichia coli) K-12 strain and its derived strain (for example, JM109 strain), Escherichia coli B strain and its derived strain (for example, BL21 strain), Bacillus subtilis (for example, Bacillus subtilis, etc.), lactic acid bacteria (for example, Lactococcus lactis, etc.), other bacteria (Corynebacterium glutamicum, Brevibacillus choshinensis, etc.), yeast (for example, Saccharomyces cerevisiae, Pichia pastoris, Schizosaccharomyces pombe, etc.), filamentous fungi (for example, Aspergillus oryzae, A. sojae, A. niger, etc.), etc.
In one embodiment of the present invention, the present invention is a method for producing LDH, which comprises culturing the above-mentioned host cell.
In one embodiment of the present invention, the present invention is a method for improving stability of LDH which comprises, in an amino acid sequence represented by SEQ ID NO: 3 or an amino acid sequence having high identity thereto, for example. identity of 70% or more, more preferably 75% or more, further preferably 80% or more, further preferably 85% or more, further preferably 90% or more, 91% or more, 92% or more. 93% or more, 94% or more, further preferably 95% or more, 96% or more, 97% or more, 98% or more, and most preferably 99% or more, a step of deleting an N-terminus, and/or mutating one or more positions selected from the group consisting of position 54, position 156, position 349 and position 428. According to the present invention, LDH improved in stability can be produced.
In one embodiment of the present invention, the present invention is a method for improving stability of LDH which comprises, in an amino acid sequence represented by SEQ ID NO: 5 or an amino acid sequence having high identity thereto, for example. identity of 70% or more, more preferably 75% or more, further preferably 80% or more, further preferably 85% or more, further preferably 90% or more, 91% or more, 92% or more. 93% or more, 94% or more, further preferably 95% or more, 96% or more, 97% or more, 98% or more, and most preferably 99% or more, a step of deleting an N-terminus, and/or mutating position at 52. According to the present invention, LDH improved in stability can be produced.
In one embodiment of the present invention, the present invention is a method for improving stability of LDH which comprises, when an alignment with the amino acid sequence represented by SEQ ID NO: 3 is formed, in the particularly important region (the region corresponding to positions 110 to 502 of SEQ ID NO: 3) for the function (activity) of LDH, in an amino acid sequence represented by SEQ ID NO: 3 or an amino acid sequence having high identity thereto, for example, 70% or more, more preferably 75% or more, further preferably 80% or more, further preferably 85% or more, further preferably 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, further preferably 95% or more, 96% or more, 97% or more, 98% or more, or most preferably 99% or more, a step of deleting an N-terminus, and/or mutating one or more positions selected from the group consisting of position 54, position 156, position 349 and position 428. According to the present invention, LDH improved in stability can be produced.
Activity of the LDH can be measured using this principle of action, for example, using the following measurement system which uses phenazine methosulfate (PMS) and 2,6-dichloroindophenol (DCIP) as electron acceptors.
Specifically, first, in (Reaction 1), accompanied with oxidation of L-lactic acid, PMS (reduced form) is formed. Then, by (Reaction 2) proceeding subsequently, accompanied with oxidation of PMS (reduced form), DCIP is reduced. The degree of disappearance of this “DCIP (oxidized form)” is detected as an amount of change in absorbance at a wavelength of 520 nm, and enzyme activity can be obtained based on this amount of change.
Specifically, activity of LDH can be measured according to the following procedure. 170 μL of IM potassium phosphate buffer (pH 7.5), 300 μL of 50 mM DL-lactic acid solution, 250 μL of 1.8 mM DCIP solution and 680 μL of ultrapure water are mixed, and maintained at 37° C. for 2 minutes or longer. Then, 50 μL of 30 mM PMS solution and 50 μL of an enzyme sample solution are added to start the reaction. Absorbance at the start of the reaction and absorbance with a lapse of time are measured, the amount of decrease in absorbance at 520 nm per minute (ΔA520) accompanied with the progress of the enzyme reaction is obtained, and LDH activity is calculated according to the following numerical formula 1. At this time, LDH activity is defined as 1 U, which is the amount of enzyme that reduces 1 μmol of DCIP per minute in the presence of L-lactic acid at a concentration of 10 mM at 37° C.
Incidentally, 1.5 in the formula represents a liquid amount (mL) of reaction reagent + enzyme reagent, 6.8 represents a millimolar molecular extinction coefficient (mM−1cm−1) of DCIP under the present activity measurement condition, 0.05 represents a liquid amount (mL) of an enzyme solution, 1.0 represents an optical path length (cm) of a cell, ΔA520, blank represents a decreased amount in absorbance at 520 nm per minute when the reaction is started by adding 10 mM potassium phosphate buffer (pH 6.0) containing 0.15% (w/v) of bovine serum albumin in place of an enzyme sample solution, and Df represents a number of diluted fold.
Thermal stability of LDH can be evaluated by heating LDH at a predetermined temperature for only a predetermined time, and comparing the activity before and after heating. Specifically, a 150 mM potassium phosphate buffer (pH 7.5) containing 0.15% (w/v) bovine serum albumin at a final concentration which contains LDH is allowed to stand on ice, and after heated to a predetermined temperature (for example, it can be 45°° C., 50° C., 55° C. or 60° C.) for 15 minutes, respectively, LDH activity is measured. By setting the LDH activity of the LDH solution allowed to stand on ice without subjecting to heat treatment to be 100, activity of the LDH solution after heating is calculated, whereby a residual activity rate (%) can be measured.
The “improvement of stability” referred to in this disclosure include not only “improvement of thermal stability in a solution state”, but also “improvement of thermal stability in a dry state”, or “improvement of thermal stability in a drying step”, or “improvement of storage stability (long-term stability) in a solution state” or “improvement of storage stability (long-term stability) in a dry state”.
That is, the “improvement of stability” referred to in this disclosure means that a residual activity rate (%) of LDH which is a value in which after a composition containing LDH is, in the coexistence of a specific stabilizer, subjected to heat treatment for a certain period of time under a certain temperature condition, or after long-term storage, is increased as compared with the state before introducing the above-mentioned mutation.
Specifically, the residual activity rate (%) can be obtained by measuring the LDH activity value (a) of the solution before heat treatment or before long-term storage, and the LDH activity value (b) after heat treatment or after long-term storage are each measured, and calculating ((b)/(a)×100). When the residual activity rate (%) of LDH after introduction of mutation which is after heat treatment or long-term storage is calculated, which is defined to be A, and when the residual activity rate (%) calculated by subjecting LDH before introduction of mutation which is a subject of comparison to the same treatment, which is defined to be B, and if A/B>1, it is evaluated that the stability of LDH has improved.
Hereinafter, the present disclosure will be explained more specifically with reference to Examples. Provided that the technical scope of the present disclosure is not limited in any way by these examples.
578 amino acids represented by SEQ ID NO: 1 which is an amino acid sequence of Pichia kudriavzevii-derived LDH (PkLDH) and 506 amino acids of Saccharomyces cerevisiae-derived LDH (ScLDH) represented by SEQ ID NO: 2 are compared, and 1509 bp gene (containing stop codon TAA) represented by SEQ ID NO: 4, which encodes the 502 amino acids represented by SEQ ID NO: 3 from which positions 2 to 77 of SEQ ID NO: 1 have been deleted, was obtained as double-stranded DNA by PCR of a gene fragment which is a conventional method. Similarly, 1503 bp gene (containing stop codon TAA) represented by SEQ ID NO: 6, which encodes the 500 amino acids represented by SEQ ID NO: 5, was obtained as double-stranded DNA by PCR of a gene fragment which is a conventional method. These genes were inserted into the multiple cloning site of plasmid pKK223-3 by a conventional method to obtain a recombinant plasmid pKK223-3-PkLDH.
Using the obtained wild type (SEQ ID NO: 3) or plasmid pKK223-3-PkLDH for expressing mutant PkLDH as a template, and using synthetic oligonucleotides of SEQ ID NO: 7 to 27, and KOD-One PCR Master Mix (manufactured by Toyobo Co., Ltd.), PCR was carried out under the following conditions. The primer set used to prepare the plasmid for expressing mutant PkLDH is summarized in Table 1. That is, 25 μL of KOD-One PCR Master Mix, 50 ng of pKK223-3-PkLDH, and 15 pmol each of the above-mentioned synthetic oligonucleotides were added, and the total volume was made up to 50 μL with sterilized water. The prepared reaction solution was incubated at 94° C. for 2 minutes using a thermal cycler (manufactured by Bio-Rad), subsequently, the cycle of “98° C. for 10 sec”-“55° C. for 5 sec”-“68° C. for 40 sec” was repeated 7 to 15 times. The DNA thus obtained was treated with the restriction enzyme DpnI (available from NEW ENGLAND BIOLABS) to cleave the remaining template DNA, and when point mutation is to be introduced, E. coli JM109 was transformed using the reaction solution as such, and spread on LB-100 μg/mL ampicillin (hereinafter referred to as Amp) agar medium. When a part of the amino acid sequence is to be deleted, to 2.0 μL of DpnI-treated PCR product were added 5.0 μL of Ligation high Ver. 2 (manufactured by Toyobo Co., Ltd.), 1.0 μL of 5 U/μL T4 polyucleotide Kinase (manufactured by Toyobo Co., Ltd.), and 7.0 μL of sterilized water, and the mixture was reacted at 16° C. for 1 hour and the resulting material was used for transformation. The grown colonies were inoculated on 2.5 mL of an LB-Amp medium [1% (w/v) Bact™ Tryptone, 0.5% (w/v) peptone, 0.5% (w/v) NaCl, and 100 μg/mL Amp] and cultured with shaking at 37° C. for 20 hours to obtain a cultured product. This cultured product was centrifuged at 15,000 rpm for 5 minutes to collect bacteria and obtain bacterial cells. Then, a recombinant plasmid was extracted from the bacterial cells using FastGene Plasmid Mini Kit (manufactured by Nippon Genetics Co., Ltd.) and purified to obtain DNA.
E. coli JM109 or BL21 strain was used as LDH producing bacteria. First, transformed E. coli JM109 or BL21 was picked from a colony of the cultured strain on an LB plate medium (containing 100 μg/mL Amp) in advance with a toothpick, cultured with shaking at 30° C. and 180 rpm for 20 hours in a small test tube in which 4 mL of an LB medium (containing 100 μg/mL Amp and 0.1 mM isopropyl-β-thiogalactopyranoside (hereinafter referred to as IPTG)) was charged.
After completion of the culture, the culture solution was centrifuged at 7,000 rpm and 4° C. for 5 minutes and the supernatant was removed, and the bacterial cells were collected. Then, the obtained bacterial cells were suspended in 600 μL of 150 mM potassium phosphate buffer (pH 7.5).
The above-mentioned bacterial cells suspension was sonicated using an ultrasonic homogenizer US-150E (manufactured by NIHONSEIKI KAISHA LTD.) suspension until the suspension became translucent, and centrifuged at 15,000 rpm and 4° C. for 5 minutes to recover the supernatant. Using this supernatant of bacterial cell crushed liquid (hereinafter referred to as crude enzyme), enzyme activity was measured.
Using PkLDH crude enzyme obtained as mentioned above, in accordance with the evaluation method of the thermal stability of LDH mentioned above, by comparing residual activity rate (%) before and after introducing mutation of LDH, search of mutation which improves stability of PkLDH was carried out.
Thermal stability of LDH was evaluated by heating LDH at a predetermined temperature for only a predetermined time, and comparing the activity before and after heating. Specifically, a 150 mM potassium phosphate buffer (pH 7.5) containing 0.15% (w/v) bovine serum albumin as a final concentration which contains LDH was allowed to stand on ice, and after heating at 55° C. for 15 minutes, respectively, LDH activity was measured. Also, the LDH activity of the LDH solution allowed to stand on ice without subjecting to heat treatment was measured, and the activity is set to be 100, activity of the LDH solution after heating was calculated, whereby a residual activity rate (%) was measured. Specifically, the residual activity rate (%) was calculated by measuring the LDH activity value (a) of the solution before heat treatment or before long-term storage, and the LDH activity value (b) after heat treatment or after long-term storage are each measured, and calculating ((b)/(a)×100).
The extent of the effect of improving stability of LDH by introducing various mutations was determined by measuring the residual activity rate (%) of LDH after introducing various mutations and comparing it with the residual activity rate (%) before introducing the mutation.
Specifically, when the residual activity rate of the crude enzyme to be compared was set to 1, the relative value of the residual activity rate of the enzyme after introducing mutation was calculated, and if this value was greater than 1, it was considered to have an effect of improving stability. For example, if the residual activity rate of the crude enzyme to be compared was 80% and the residual activity rate of the enzyme after mutation introduction was 85%, the relative value of the residual activity will be 1.06.
Activity of LDH was measured according to the following procedure. 170 μL of 1 M potassium phosphate buffer (pH 7.5), 300 μL of 50 mM L-lactic acid solution 250 μL of 1.8 mM DCIP solution and 680 μL of ultrapure water were mixed, and maintained at 37° C. for 2 minutes or longer. Then, 50 μL of 30 mM PMS solution and 50 μL of an enzyme sample solution were added to start the reaction. Absorbance at the start of the reaction and absorbance with a lapse of time were measured, the amount of decrease in absorbance at 520 nm per minute (ΔA520) accompanied with the progress of the enzyme reaction was obtained, and LDH activity was calculated according to the following numerical formula 1. At this time, LDH activity was defined as 1 U, which is the amount of enzyme that reduces 1 μmol of DCIP per minute in the presence of L-lactic acid at a concentration of 10 mM at 37° C.
Incidentally, 1.5 in the formula represents a liquid amount (mL) of reaction reagent + enzyme reagent, 6.8 represents a millimolar molecular extinction coefficient (mM−1cm−1) of DCIP under the present activity measurement condition, 0.05 represents a liquid amount (mL) of an enzyme solution, 1.0 represents an optical path length (cm) of a cell, ΔA520, blank represents a decreased amount in absorbance at 520 nm per minute when the reaction is started by adding 10 mM potassium phosphate buffer (pH 6.0) containing 0.15% (w/v) of bovine serum albumin in place of an enzyme sample solution, and Df represents a number of diluted fold.
In accordance with the above-mentioned evaluation method of thermal stability, using LDH solution (2 to 3 U/mL) containing 150 mM of potassium phosphate buffer and 0.15% (w/v) bovine serum albumin (BSA), the residual activity rate of LDH was calculated.
In Table 2, the relative values of the residual activity rate of LDH containing N-terminal deletion according to the present invention is shown with the residual activity rate of the wild type PkLDH (Comparative Example) represented by SEQ ID NO: 3 being 1. In addition, in Table 3, the relative values of the residual activity rate of LDH containing N-terminal deletion according to the present invention is further shown with the residual activity rate of LDH (Present invention 4) having F428L in the wild type PkLDH represented by SEQ ID NO: 3 being 1.
Focusing on the amino acids on the N-terminal side of PkLDH, as a result of intensive investigation, as shown in Tables 2 and 3, among the amino acid sequences of PkLDH represented by SEQ ID NO: 3, it became clear that thermal stability of PkLDH is improved by introducing deletion of positions 2 to 75 (ΔA2 to L75), deletion of positions 2 to 83 (ΔA2 to V83), deletion of positions 2 to 91 (ΔA2 to L91) and, F428L mutation and deletion of positions 2 (F428L/ΔA2), F428L and deletion of positions 2 to 3 (F428L/ΔA2 to T3), F428L and deletion of positions 2 to 4 (F428L/ΔA2 to G4), F428L and deletion of positions 2 to 5 (F428L/ΔA2 to S5), F428L and deletion of positions 2 to 6 (F428L/ΔA2 to D6), or F428L and deletion of positions 2 to 7 (F428L/ΔA2 to S7) into PkLDH. In addition, with regard to the mutant (ΔA2 to N109) in which positions 2 to 109 of PkLDH had been deleted, LDH activity could be detected whereas heat resistance has not been evaluated.
In Table 4, the relative values of the residual activity rate of LDH containing Y156F mutation, Y349F mutation and F428L mutation according to the present invention is further shown with the residual activity rate of LDH (Present invention 6) having F428L in the wild type PkLDH represented by SEQ ID NO: 3 and containing deletion of positions 2 to 3 being 1.
As a result of intensive search for mutations that further improve the stability of F428L/ΔA2 to T3 obtained as mentioned above, as shown in Table 4, it became clear that the resulting materials had higher stability than the original one by introducing Y156F mutation, Y349F mutation and F428L mutation.
In Table 5, the relative values of the residual activity rate of LDH which further contains A54C and the amino acid sequence (hereinafter referred to as PkLDH-C) represented by SEQ ID NO: 5 with the residual activity rate of LDH (Present invention 12) having Y156F, Y349F, F428L in the wild type PkLDH represented by SEQ ID NO: 3 and containing deletion of positions 2 to 3 being 1.
As a result of intensive search for mutations that further improve the stability of PkLDH/Y156F/Y349F/F428L/ΔA2 to T3 obtained as mentioned above, as shown in Table 5, it became clear that the material into which A54C mutation had been introduced, and LDH having the amino acid sequence represented by SEQ ID NO: 5 had higher stability than the original one.
For reference, the results of alignment of the amino acid sequence of SEQ ID NO: 3 and SEQ ID NO: 5 are shown in
Subsequently, as a result of intensive search for mutations that further improve stability of LDH, as shown in Table 6, it became clear that the material in which S52C mutation (corresponding to A54C mutation of SEQ ID NO: 3) was introduced into PkLDH-C had higher stability than the original one.
FP4787PCT.XML
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-127638 | Aug 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/028959 | 7/27/2022 | WO |
