Table III.

Specificity of sugar phosphates as substrates for wild-type and mutant enzyme SK198ALwt

SubstrateSubstrate ConcentrationWild TypeSK198ALwt
mm units mg−1
Glc-1-P248  ± 11.5  ± 0.2
1055.8  ± 4.710.4  ± 0.9
6-deoxy-Glc-1-P213.6  ± 0.30.085  ± 0.001
1012.5  ± 0.10.62  ± 0.04
6F-Glc-1-P213.0  ± 0.50.044  ± 0.002
1018.1  ± 0.60.472-a
2F-Glc-1-P21.00.007  ± 0.001
104.0  ± 0.10.018  ± 0.03
Man-1-P21.7  ± 0.10.010  ± 0.001
104.1  ± 0.20.058  ± 0.003
3-deoxy-Glc-1-P20.5  ± 0.10.010  ± 0.006
101.3  ± 0.10.017  ± 0.002
3F-Glc-1-P20.05  ± 0.01≤0.002
100.15  ± 0.01≤0.002
Gal-1-P20.16  ± 0.03≤0.003
100.28  ± 0.04≤0.002
GlcUA-1-P2≤0.01≤0.001
10≤0.01≤0.02

Reactions were performed in the synthesis direction as described in “Materials and Methods,” with the presence of sugar phosphates as indicated. Data represent the average of two duplications ±sd. One unit of enzyme activity is expressed as the amount of enzyme required to form 1 μmol of ADPGlc per minute at 37°C assayed in either the synthesis or the pyrophosphorolysis direction. The lower limit of detection of enzyme activity for the wild type is 0.01 unit mg−1, and for the mutant enzyme SK198ALwt it is 0.001 unit mg−1when a sufficient amount of enzyme was used in the assay, as indicated in the text.

    • F2-a Single determination.