Porcine kidney betaine aldehyde dehydrogenase: purification and properties
1998
Guzman-Partida, A.M. | Valenzuela-Soto, E.M.
Significant betaine aldehyde dehydrogenase activity was found in porcine kidney. The enzyme was purified 320-fold with an overall recovery of 11%. It had a specific activity of 115.8 nkats/mg protein and proved to be homogeneous by SDS-PAGE with a subunit molecular mass of 52 kDa. IEF studies showed three bands with pI values of 5.74, 5.68 and 5.58, respectively. The enzyme was stable in a pH range between 5.0 and 10.0 and the optimum pH was 9.5. The reaction is highly specific for NAD+ and betaine aldehyde, although acetaldehyde, butyraldehyde and glyceraldehyde can be used. Estimated values of Km at pH 8.0 and 25 degrees C were 127 micromolar for betaine aldehyde and 40 micromolar for NAD+. The reaction could not be reversed even at high glycine betaine concentrations. The enzyme was not activated by salts at high concentrations but it was salt tolerant--retaining 50% of maximal activity at 1.0 M K+ and Na+. It is inferred that salt tolerance is an essential property for an enzyme participating in the cellular synthesis of an osmoprotectant. Proline, glycerol, sucrose and mannitol had a little effect on the enzyme activity while glycine betaine had an inhibitory effect.
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