Inactivation and unfolding of the hyperthermophilic inorganic pyrophosphatase from Thermus thermophilus by sodium dodecyl sulfate

• Published in: International journal of molecular sciences Vol. 10; no. 6; pp. 2849 - 2859
• Main Authors: Mu, Hang, Zhou, Sheng-Mei, Xia, Yong, Zou, Hechang, Meng, Fanguo, Yan, Yong-Bin
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.06.2009; Molecular Diversity Preservation International (MDPI)
• Subjects: Circular Dichroism; Enzymes; hyperthermophilic enzyme; inactivation; inorganic pyrophosphatase; Inorganic Pyrophosphatase - chemistry; Inorganic Pyrophosphatase - genetics; Inorganic Pyrophosphatase - metabolism; Metabolism; mixed type reversible inhibition; protein folding; Protein Unfolding; Proteins; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Sodium; sodium dodecyl sulfate; Sodium Dodecyl Sulfate - chemistry; Spectrophotometry, Ultraviolet; Thermus thermophilus; Thermus thermophilus - enzymology; Yeast; China; Thermus thermophilus; hyperthermophilic enzyme; inactivation; sodium dodecyl sulfate; protein folding; inorganic pyrophosphatase; mixed type reversible inhibition
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms10062849

Inorganic pyrophosphatase (PPase, EC 3.6.1.1) is an essential constitutive enzyme for energy metabolism and clearance of excess pyrophosphate. In this research, we investigated the sodium dodecyl sulfate (SDS)-induced inactivation and unfolding of PPase from Thermus thermophilus (T-PPase), a hyperthermophilic enzyme. The results indicated that like many other mesophilic enzymes, T-PPase could be fully inactivated at a low SDS concentration of 2 mM. Using an enzyme activity assay, SDS was shown to act as a mixed type reversible inhibitor, suggesting T-PPase contained specific SDS binding sites. At high SDS concentrations, T-PPase was denatured via a two-state process without the accumulation of any intermediate, as revealed by far-UV CD and intrinsic fluorescence. A comparison of the inactivation and unfolding data suggested that the inhibition might be caused by the specific binding of the SDS molecules to the enzyme, while the unfolding might be caused by the cooperative non-specific binding of SDS to T-PPase. The possible molecular mechanisms underlying the mixed type inhibition by SDS was proposed to be caused by the local conformational changes or altered charge distributions.