TABLE 1.

Benzaldehyde formation from phenylpyruvic acid in the presence of different metal ions

Addition to reaction mixturea	Benzaldehyde produced (mM)
No addition	<0.001
350 μM Cu(II)	4.19
100 μM Cu(II)	2.13
50 μM Cu(II)	1.03
100 μM Cu(II) + 200 μM EDTA	<0.001
100 μM Cu(II) flushed with N2 gas	<0.001
100 μM Fe(II)	0.22
100 μM Fe(III)	1.88
100 μM Mn(II)	1.57
10 μM Mn(II)	0.55
10 μM Mn(III)	0.38
100 μM Zn(II)	<0.001
350 μM Mg(II)	<0.001

^aEach reaction mixture contained 8 mM phenylpyruvic acid in 50 mM Tris buffer, pH 8.0. Incubations were performed at 37°C. In all cases, SO₄²⁻ was the counterion of the metal ion added.