Table 4.

Steady-State Kinetic Parameters for the Proline Dehydrogenase and l-Glutamate γ-Semialdehyde Dehydrogenase Activities of Proline Utilization A

	PRODH (variable substrate is Pro)			GSALDH (variable substrate is P5C)
PutA	kcat (s−1)	Km (mM)	kcat/Km (M−1·s−1)	kcat (s−1)	Km (μM)	kcat/Km (M−1·s−1)
BjPutAa	2	31	65	2.2	200	11,000
BjPutAb	5.6	150	37
BjPutAc	3.1	43	72	3.4	420	8100
RcPutAd	20.7	54.3	383	7.3	1530	4800
RcPutAe	1.0	5.6	179
EcPutAf	5.2	42	124	5.16	2000	2600
EcPutAg	12	100	120
EcPutAg	6.7	230	29
EcPutAh	0.43	1.5	287
GsPutAi	0.67	89	7	7.5	35	214,000
HpPutAj	8	146	56
CfPutAk	2.6	145	18	1.7	54	32,000

^aProline parameters were determined at 23°C with CoQ₁ fixed at 100 μM (121). The P5C parameters were determined at saturating NAD⁺ concentration.

^bDCPIP assay (52).

^cCoQ₁ fixed at 250 μM as the electron acceptor in the PRODH assays (4).

^dProline parameters were determined with [DCPIP] fixed at 75 μM (70). The P5C parameters were determined with [NAD⁺] fixed at 200 μM.

^eCoQ₁ as the electron acceptor (3).

^fProline parameters were determined by fitting to a two-site ping-pong mechanism with CoQ₁ as the electron acceptor (85). The P5C parameters were obtained by fitting to an ordered ternary mechanism (84). k_cat for the coupled PRODH-GSALDH reaction from Moxley et al. (84).

^gDCPIP assay (156, 157).

^hParameters for proline were estimated from the oAB assay with membrane vesicles providing the electron acceptor for the FAD (85).

ⁱProline parameters were determined with menadione fixed at 100 μM (117). The P5C parameters were determined with [NAD⁺] fixed at 200 μM.

^jDCPIP assay (53).

^kPRODH parameters were determined from the DCPIP assay (50).

oAB, o-aminobenzaldehyde; DCPIP, 2,6-dichlorophenolindophenol; FAD, flavin adenine dinucleotide; HpPutA, Helicobacter pylori proline utilization A; PRODH, proline dehydrogenase; RcPutA, Rhodobacter capsulatus proline utilization A.