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. Author manuscript; available in PMC: 2012 Oct 5.
Published in final edited form as: Bioconjug Chem. 2009 Mar 18;20(3):608–618. doi: 10.1021/bc800534r

Table 2.

Kinetic parameters for donor substrates UDP-Gal and UDP-GalNAc and the acceptor substrate lactose with wild-type (WT with Ser347) and mutant enzymes.

UDP-Gal
Enzyme Ka
(mmol)		 Kb
(mmol)		 Kia
(mmol)		 Kib
(mmol)		 kcat
(s−1)		 kcat/Ka
(s−1 mmol)		 kcat/Kb
(s−1 mmol)
α1,3 GalT 280HAA282 (WT) 0.790±0.001 4.50±0.01 0.13±0.01 0.74±0.02 3.40 4.30 7.5×10−1
α1,3 GalT 280AGG282 0.042±0.012 270± 21 0.004±0.0007 25.70±3 0.02 0.50 7.4×10−5
α1,3 GalT 280SGG282 0.070±0.001 180±24 0.014±0.001 36±5 0.10 1.40 5.5×10−4
UDP-GalNAc
Enzyme Ka
(mmol)		 Kb
(mmol)		 Kia
(mmol)		 Kib
(mmol)		 kcat
(s−1)		 kcat/Ka
(s−1 mmol)		 kcat/Kb
(s−1 mmol)
α1,3 GalT 280HAA282 (WT) N/A N/A N/A N/A N/A N/A N/A
α1,3 GalT 280AGG282 0.500±0.04 258±25 0.068±0.002 36.1±2 0.30 0.60 1.1×10−3
α1,3 GalT 280SGG282 0.740±0.001 330±30 0.101±0.004 45.8±8 0.40 0.50 7.0×10−4