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Table 1 Kinetic parameters of Zea mays tryptophan synthase and comparison with characterized homologs.

From: Characterisation of the tryptophan synthase alpha subunit in maize

Reaction Recombinant Enzyme(s) Substrate KM (μM) kcat (s-1) kcat/KM(mM-1 s-1)
α ZmTSA IGP 458 ± 94 0.006 ± 0.002 0.013
α ZmTSA+ZmTSB1 IGP 52 ± 6 0.019 ± 0.004 0.37
β ZmTSB1 Indole 24 ± 4 0.29 ± 0.04 12.1
β ZmTSA+ZmTSB1 Indole 28 ± 6 0.44 ± 0.07 15.7
αβ ZmTSA+ZmTSB1 IGP 47 ± 9 0.45 ± 0.06 9.6
α ZmTSAlike IGP n. d. n. d. n. d.
α ZmTSAlike+ZmTSB1 IGP n. d. n. d. n. d.
α BX1 [18] IGP 13 2.8 215
α IGL [17] IGP 100 2.3 23
α EcTSA 1) IGP 480 0.002 0.004
α EcTSA + EcTSB 1) IGP 27 0.2 7.4
α StTSA + StTSB 2) IGP 100 0.14 1.4
β StTSA + StTSB 2) Indole 15 3.6 240
αβ StTSA + StTSB 2) IGP 20 3 150
  1. 1) [31], Ec: E. coli.
  2. 2) [35], St: S. typhimurium.
  3. n. d.: For ZmTSAlike no IGP turnover was detected.