Gold Nanoparticle-Protein Conjugate Dually-Responsive to pH and Temperature for Modulation of Enzyme Activity

25 Pages Posted: 1 Feb 2019

See all articles by Ya Sun

Ya Sun

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

Zhenhua Li

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

Jingxian Wu

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

Zhiqiang Wang

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

Yishi Dong

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

Hongwei Wang

Soochow University - State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials; Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

John L. Brash

McMaster University - Department of Chemical Engineering

Lin Yuan

Soochow University - State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials; Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

Hong Chen

Soochow University - State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials; Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

Date Written: February 1, 2019

Abstract

Regulation of the activity and stability of enzymes is important for their biological and biomedical applications. In this regard, considerable attention has been paid to the regulation of enzyme activity by controlling steric effects in protein-thermoresponsive polymer conjugates via temperature change. However, it is difficult to accomplish on/off regulation of activity via steric effects alone. In this work, pH- and temperature- dually-responsive gold nanoparticles (AuNPs) conjugated to poly (N-isopropylacrylamide) (pNIPAM) and poly(methacrylic acid) (pMAA), designated AuNP-pNIPAM-pMAA, are proposed in this work for the regulation of enzyme activity with high precision. Using these particles adsorbed with inorganic pyrophosphatase (PPase) as a model enzyme (AuNP-PPase-pNIPAM-pMAA), it was shown that, by changes in pH and temperature leading to changes in “steric covering” of the protein active site via interpolymer hydrogen bonding, the activity of PPase could be closely regulated. At 25 °C and pH 5.0, the steric covering of pNIPAM and the interpolymer hydrogen bonding between pNIPAM and pMAA gave a cage-like “locking in” structure in the protein active site as the “hidden” state, with a very low specific activity of only 0.2 Kat/Kg, around 2 % of its normal activity. At 45 °C and pH 8.0, the cage structure did not form due to the lack of coverage by the collapsed pNIPAM chains and the inability of the dissociated carboxyl groups in pMAA to form hydrogen bonds, leaving the protein active center fully exposed as the “available” state, and resulting in a high specific activity of 8.3 Kat/Kg. Thus the activity of the enzyme in the conjugate is almost totally suppressed at 25 °C/pH 5.0 and completely recovered at 45 °C/pH 8.0. The controllable range of activity is thus very wide, i.e., from 2 to 100 %. The AuNP-PPase-pNIPAM-pMAA conjugate also has strong resistance to trypsin digestion. In addition, it was shown that after cycling three times between the “hidden” and “available” states, the conjugate retained more than 85 % of its initial activity, showing that this system can be cycled and used multiple times without significant loss of activity. It is concluded that this dual-responsive gold nanoparticle-protein-polymer conjugate has great potential in applications requiring close control of protein activity under complex environmental conditions.

Keywords: inorganic pyrophosphatase, protein activity, dual-responsive conjugate, gold nanoparticle

Suggested Citation

Sun, Ya and Li, Zhenhua and Wu, Jingxian and Wang, Zhiqiang and Dong, Yishi and Wang, Hongwei and Brash, John L. and Yuan, Lin and Chen, Hong, Gold Nanoparticle-Protein Conjugate Dually-Responsive to pH and Temperature for Modulation of Enzyme Activity (February 1, 2019). Available at SSRN: https://ssrn.com/abstract=3326755 or http://dx.doi.org/10.2139/ssrn.3326755

Ya Sun (Contact Author)

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

No. 1 Shizi Street
Taipei, Jiangsu 215006
Taiwan

Zhenhua Li

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

No. 1 Shizi Street
Taipei, Jiangsu 215006
Taiwan

Jingxian Wu

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

No. 1 Shizi Street
Taipei, Jiangsu 215006
Taiwan

Zhiqiang Wang

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

No. 1 Shizi Street
Taipei, Jiangsu 215006
Taiwan

Yishi Dong

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

No. 1 Shizi Street
Taipei, Jiangsu 215006
Taiwan

Hongwei Wang

Soochow University - State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials

Suzhou
China

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

No. 1 Shizi Street
Taipei, Jiangsu 215006
Taiwan

John L. Brash

McMaster University - Department of Chemical Engineering

1280 Main Street West
Hamilton, Ontario L8S 4M4 L8S 4L8
Canada

Lin Yuan

Soochow University - State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials

Suzhou
China

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

No. 1 Shizi Street
Taipei, Jiangsu 215006
Taiwan

Hong Chen

Soochow University - State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials

Suzhou
China

Soochow University - The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou

No. 1 Shizi Street
Taipei, Jiangsu 215006
Taiwan

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