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. Author manuscript; available in PMC: 2010 Jul 26.
Published in final edited form as: Biochemistry. 2008 May 14;47(23):6226–6232. doi: 10.1021/bi800351a

Table 1.

Comparison of the kinetic parameters for the polymorphic variants and pathogenic mutants of CGL

CGL variant or mutant
substrate parameter S403 I403 T67I Q240E
Csta V max b 2.3 ± 0.2 2.6 ± 0.1 0.6 ± 0.1 0.03 ± 0.005
KM, mM 0.4 ± 0.1 0.6 ± 0.1 0.6 ± 0.1 0.72 ± 0.16
kcat, s−1 1.7 ± 0.2 1.9 ± 0.08 0.45 ± 0.07 0.02 ± 0.004
kcat/KMc 4.2 3.2 0.86 0.028
Hcy V max 4.7 ± 0.3 5.0 ± 0.2 1.1 ± 0.2 N.D.d
KM, mM 5.4 ± 1.0 7.0 ± 1.3 8.0 ± 2.1 N.D.
kcat, s−1 3.5 ± 0.2 3.7 ± 0.2 0.82 ± 0.16 N.D.
kcat/KM 0.65 0.53 0.10 N.D.
Cys V max 0.9 ± 0.1 0.9 ± 0.1 0.4 ± 0.03 N.D.
KM, mM 3.5 ± 1.2 3.4 ± 1.4 4.1 ± 1.7 N.D.
kcat, s−1 0.67 ± 0.07 0.67 ± 0.07 0.30 ± 0.02 N.D.
kcat/KM 0.19 0.20 0.07 N.D.
a

Cst, Hcy, and Cys refer to cystathionine, homocysteine, and cysteine, respectively.

b

Vmax is expressed in units of μmol of cysteine or H2S formed min−1 mg−1 of protein at 37 °C.

c

kcat/KM is expressed in units of mM−1 s−1.

d

N.D. is not detected.