Inversion of allosteric effect of arginine on N-acetylglutamate synthase, a molecular marker for evolution of tetrapods

Table 3 Effects of L-arginine on vertebrate, plant and bacterial NAGS.

	NAGS Specific Activity (μmoles min^-1mg^-1)
Organism		+ 1 mM Arg
Human	19.293 ± 0.384^a	29.285 ± 1.211
Mouse	29.523 ± 1.076	46.541 ± 5.602
African clawed frog	0.438 ± 0.011	0.528 ± 0.004
Western clawed frog	0.098 ± 0.002	0.136 ± 0.005
Zebrafish	10.638 ± 0.090	5.475 ± 0.121
Pufferfish	20.887 ± 0.278	15.898 ± 0.141
X. campestris	111.741 ± 1.669	nd^b
M. maris	62.004 ± 3.751	0.572 ± 0.136
Arabidopsis	9.116 ± 0.279	nd
E. coli	5.859 ± 0.220	1.840 ± 0.032

^aActivities are averages of three measurements and the associated standard errors.
^bNot detectable.

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