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. Author manuscript; available in PMC: 2017 Jun 1.
Published in final edited form as: Biochemistry. 2015 Oct 5;54(41):6392–6401. doi: 10.1021/acs.biochem.5b00942

Table 2.

Specific activities and metal contents of urease samples enriched from cells containing selected KaUreD variantsa

KaUreD variant Specific activity U/mg protein (% WT) Ni per UreABC (% WT) Zn per UreABC Fe per UreABC
WT(-Ni) pKK17D 0 0.004 (4 × 10−5) 0.13 0.27
WT pKKDG 1690 (100) 1.1 (100) 0 0.02
D63A pKKDG 434 (25.7) 0.54 (49.1) 0.16 0.21
D63Q pKKDG 55.7 (3.29) 0.22 (20.0) 0.34 0.07
S85K pKKDG 487 (28.8) 0.39 (35.5) 0.06 0.30
D142A pKKDG 14.1 (0.84) 0.07 (6.4) 0.52 0.14
E176A pKKDG 1080 (63.7) 0.51 (46.4) 0.09 0.11
E176Q pKKDG 375 (22.2) 0.43 (39.1) 0.03 0.13
R211A pKKDG 1230 (72.4) 0.76 (69.1) 0.21 0.29
a

The urease samples were enriched from cell-free extracts of E. coli pKKD*G grown in LB containing 1 mM NiCl2, except for a sample of urease apoprotein that was obtained from E. coli pKK17D grown in LB lacking nickel (-Ni). Units of urease activity are μmole min−1 (mg protein)−1. Metal contents were determined by inductively coupled plasma-atomic emission spectroscopy.