Figure 2 : Biochemical properties of DtHNL isoenzymes.

From: Enzyme discovery beyond homology: a unique hydroxynitrile lyase in the Bet v1 superfamily

Figure 2

DtHNL1 ; DtHNL2 ; DtHNL3 ; DtHNL4 . Grey dashed lines indicate the spontaneous degradation of racemic mandelonitrile in a negative control reaction without enzyme addition (background reaction). Standard enzymatic assay was performed by monitoring benzaldehyde formation at 280 nm. Values were obtained from the average of a minimal of two and a maximum of three independent samples, each of which is the average of two or three technical replicates. Standard deviations are within the 20% threshold (or 25% for temperature profile). For clarity, error bars have been omitted. (a) pH profile. Relative activity of DtHNL isoenzymes at different pH values from 2.0 to 7.0. The assay was performed in HCl-potassium chloride buffer (filled symbols), or sodium citrate-phosphate buffer (empty symbols). Activity of DtHNL1 and 2 at pH 7.0 is not depicted due to high standard deviations. (b) Temperature profile. Relative activity of DtHNL isoenzymes at different temperatures from 10 to 50 °C. The assay was performed at pH 5.0. Omitted points are due to high standard deviations. Enzyme stability at pH 2.5 (c) and at pH 4.0 (d). Activity after incubation of DtHNL isoenzymes at pH 2.5 or 4.0, respectively, and 8 °C. Relative activity is based on the activity before incubation.