Table 2 Cu fractionation induced by amino acids (mean ± 2 SE).

From: Metal-binding amino acid ligands commonly found in metalloproteins differentially fractionate copper isotopes

Ligand

Dominant ligand

Amino acid:Cu ratioa

# Replicate experiments

ffree (%)

δ65Cufree (‰)

δ65Cucomplex (calculated, ‰)

Δ65Cucomplex-free (calculated, ‰)

Cysteine

S

1:2

6

38.0 ± 5.2

 + 1.38 ± 0.08

 + 0.89 ± 0.14

− 0.48 ± 0.18

Histidine

N

1:1

2

84.0 ± 1.6

 + 0.79 ± 0.07

 + 0.78 ± 0.03

− 0.01 ± 0.04

Glutamate

O

1:1

3

65.9 ± 1.1

 + 0.81 ± 0.04

 + 1.07 ± 0.06

 + 0.26 ± 0.04

Aspartate

O

1:1

3

67.6 ± 1.6

 + 0.89 ± 0.03

 + 1.05 ± 0.07

 + 0.16 ± 0.10

  1. aApproximate ratio of amino acids to Cu added to experimental donor solutions.
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