Skip to main content

Table 4 Kinetic parameters for PvANR1 in assays containing varying amounts of cyanidin and NADPH

From: Proanthocyanidin accumulation and transcriptional responses in the seed coat of cranberry beans (Phaseolus vulgaris L.) with different susceptibility to postharvest darkening

Varying substrate

Product

K 0.5

(μM)

K i

(μM)

V max

(nmol min−1 mg−1)

k cat

(s−1)

k cat /K 0.5

(s−1 M−1)

Cyanidin

Epicatechina

114.2 ± 19.0

631.5 ± 119.9

11.57 ± 1.13

0.0072 ± 0.0007

65.4 ± 13.8

Cyanidin

Catechina

116.5 ± 10.7

583.8 ± 116.1

8.32 ± 0.73

0.0052 ± 0.0004

45.4 ± 6.42

NADPH

Epicatechinb

103.5 ± 7.4

-

3.34 ± 0.21

0.0021 ± 0.0001

20.1 ± 0.49

NADPH

Catechinb

102.3 ± 7.8

-

2.44 ± 0.18

0.0015 ± 0.0001

14.9 ± 1.03

  1. The K cat (also referred to as turnover rate) was calculated using a molecular mass of 37.4 kDa for the final recombinant PvANR1 preparation, following removal of the His6 tag
  2. aA non-linear regression model for substrate inhibition (as described under Methods) was used to determine apparent kinetic parameters for cyanidin. These assays were performed at a fixed NADPH concentration of 800 μM
  3. bThe Hill equation was utilized to determine kinetic parameters for NADPH. These assays were performed at a fixed cyanidin concentration of 100 μM; the Hill coefficient for epicatechin and catechin formation was 2.5 ± 0.19 and 2.5 ± 0.15, respectively