Interaction of Human Dopa Decarboxylase with L-Dopa: Spectroscopic and Kinetic Studies as a Function of pH

Table 1

Summary of pK_a values for hDDC.

Parameter	pH-independent value	pK1	pK2
𝑘cat	5.1 ± 0.4 s^−1	6.3 ± 0.1	7.9 ± 0.1
𝑘cat/Km	174 ± 3 mM^−1s^−1	6.1 ± 0.1
Absorbance at 420 nm pH titration			7.2 ± 0.1
Absorbance at 335 nm pH titration			7.3 ± 0.1
Emission fluorescence pH titration (exc. 335 nm)
emis.384 nm			7.3 ± 0.1
emis.504 nm			7.2 ± 0.1
Emission fluorescence pH titration (exc. 420 nm)
emis.504nm			7.2 ± 0.1
Amplitude ext. ald. 390 nm		6.4 ± 0.3
KD(PLP)			8.3 ± 0.2