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The effect of phosphate group binding cup coordination on the stability of the amine transaminase from Chromobacterium violaceum
KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.ORCID-id: 0000-0002-9577-832X
KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
2018 (engelsk)Inngår i: Molecular Catalysis, ISSN 2468-8231, Vol. 446, s. 115-123Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The amine transaminase from Chromobacterium violaceum (Cv-ATA) is a pyridoxal-5’-phosphate (PLP)dependent enzyme. The biological activity of this enzyme requires the formation of a holo homo dimer.The operational stability of Cv-ATA is, however, low due to dimer dissociation. At the enzyme dimeric interface, two phosphate group binding cups (PGBC) are located. Each cup coordinates the phosphate group of PLP by hydrogen bonds originating from both subunits. Hypothetically, molecular coordination of phosphate groups (PLP or free inorganic phosphate) into the PGBC can affect both dimer stabilization and enzyme activity. To test this assumption, the influence of phosphate (as a functional group in PLP or as free inorganic anions) on the stability and activity of Cv-ATA was explored by various biophysical techniques. The results show that Cv-ATA has a relatively low affinity towards PLP, which results in an excess of apo dimeric enzyme after enzyme purification. Incubation of the apo dimer in buffer solution supplemented with PLP restored the active holo dimer. The addition of PLP or inorganic phosphate into the enzyme storage solutions protected Cv-ATA from both chemical and long term storage unfolding. The use of phosphate buffer leads to faster inactivation of the holo enzyme, compared to the use of HEPES buffer. These results open up for new perspectives on how to improve the stability of PLP-dependent enzymes.

sted, utgiver, år, opplag, sider
Elsevier, 2018. Vol. 446, s. 115-123
Emneord [en]
Biocatalysis, Dimeric enzymes, PLP-dependent enzymes, Pyridoxal-5’-phosphate (PLP), Schiff base
HSV kategori
Forskningsprogram
Bioteknologi
Identifikatorer
URN: urn:nbn:se:kth:diva-224452DOI: 10.1016/j.mcat.2017.12.033ISI: 000426411900013Scopus ID: 2-s2.0-85041891410OAI: oai:DiVA.org:kth-224452DiVA, id: diva2:1191331
Merknad

QC 20180320

Tilgjengelig fra: 2018-03-18 Laget: 2018-03-18 Sist oppdatert: 2018-03-20bibliografisk kontrollert
Inngår i avhandling
1. Stability and inactivation mechanisms of two transaminases
Åpne denne publikasjonen i ny fane eller vindu >>Stability and inactivation mechanisms of two transaminases
2018 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

In the past decades, more and more enzymes are employed as biocatalysts in industrial processes because of their advantages, such as high efficiency, substrate selectivity and stereoselectivity. Among them, amine transaminases (ATAs) are pyridoxal 5’-phosphate (PLP) dependent enzymes. ATAs have gained attention for their excellent performance in chiral amine synthesis, and their broad substrate acceptance. However, the low operational stability of amine transaminases still limits their application in industry.

The amine transaminase from Chromobacterium violaceum (Cv-ATA) has been selected for further investigation for its relatively low operational stability. Co-solvents and various additives have been added to the enzyme storage solution to improve its storage stability at various temperatures. Co-lyophilization of Cv-ATA with surfactants has been applied to improve its enzymatic activity in neat organic solvents.

As a PLP-dependent dimeric enzyme, the Cv-ATA is not primarily inactivated due to tertiary structural changes. Instead, both dimer dissociation and PLP release may affect the enzyme stability. Therefore, the inactivation pathway of the Cv-ATA during operational conditions was explored. The unfolding of the enzyme was detected by several methods, and the detection of fluorescence intensity spectrum of tryptophan is extensively applied for its high sensitivity. The phosphate group of PLP can be coordinated into the phosphate group binding cup, which may influence the enzyme structural stability. Therefore, the effect of both PLP and inorganic phosphate ions (present in phosphate buffer) on the enzyme stability was explored.

The amine transaminase from Vibrio fluvialis (Vf-ATA) is another amine transaminase, which catalyses the same biocatalytic reaction and has a similar substrate scope as Cv-ATA. However, there is still a lack of data on the stability of Vf-ATA. Consequently, the operational stability of Vf-ATA in various environments was studied.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2018. s. 56
Serie
TRITA-CBH-FOU ; 2018:10
Emneord
Amine Transaminase, Operational Stability, Inactivation Pathway, Enzyme Unfolding, Phosphate Group Binding Cup
HSV kategori
Forskningsprogram
Bioteknologi
Identifikatorer
urn:nbn:se:kth:diva-224538 (URN)978-91-7729-716-1 (ISBN)
Disputas
2018-04-11, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad

QC 20180320

Tilgjengelig fra: 2018-03-20 Laget: 2018-03-19 Sist oppdatert: 2018-03-27bibliografisk kontrollert

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