Human Salivary Aldehyde Dehydrogenase: Purification, Kinetic Characterization and Effect of Ethanol, Hydrogen Peroxide and Sodium Dodecyl Sulfate on the Activity of the Enzyme

Cell Biochem Biophys. 2016 Sep;74(3):307-15. doi: 10.1007/s12013-016-0742-9. Epub 2016 Jun 21.

Abstract

Human salivary aldehyde dehydrogenase (hsALDH) enzyme appears to be the first line of defense in the body against exogenous toxic aldehydes. However till date much work has not been done on this important member of the ALDH family. In this study, we have purified hsALDH to homogeneity by diethylaminoethyl-cellulose (DEAE-cellulose) ion-exchange chromatography in a single step. The molecular mass of the homodimeric enzyme was determined to be approximately 108 kDa. Four aromatic substrates; benzaldehyde, cinnamaldehyde, 2-naphthaldehyde and 6-methoxy-2-naphthaldehyde were used for determining the activity of pure hsALDH. K m values for these substrates were calculated to be 147.7, 5.31, 0.71 and 3.31 μM, respectively. The best substrates were found to be cinnamaldehyde and 2-naphthaldehyde since they exhibited high V max /K m values. 6-methoxy-2-naphthaldehyde substrate was used for further kinetic characterization of pure hsALDH. The pH and temperature optima of hsALDH were measured to be pH 8 and 45 °C, respectively. The pure enzyme is highly unstable at high temperatures. Ethanol, hydrogen peroxide and SDS activate hsALDH, therefore it is safe and beneficial to include them in mouthwashes and toothpastes in low concentrations.

Keywords: Activity; Purification; Salivary aldehyde dehydrogenase.

MeSH terms

  • Aldehyde Dehydrogenase / chemistry
  • Aldehyde Dehydrogenase / isolation & purification
  • Aldehyde Dehydrogenase / metabolism*
  • Chromatography, Ion Exchange
  • Electrophoresis, Polyacrylamide Gel
  • Ethanol / chemistry*
  • Ethanol / metabolism
  • Fluorometry
  • Humans
  • Hydrogen Peroxide / chemistry*
  • Hydrogen Peroxide / metabolism
  • Hydrogen-Ion Concentration
  • Kinetics
  • Protein Stability
  • Saliva / enzymology*
  • Sodium Dodecyl Sulfate / chemistry*
  • Sodium Dodecyl Sulfate / metabolism
  • Temperature

Substances

  • Sodium Dodecyl Sulfate
  • Ethanol
  • Hydrogen Peroxide
  • Aldehyde Dehydrogenase