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Table 1 Binding of ferric ions by gastrin17, CCK8 and their derivatives

From: Tyrosine modification increases the affinity of gastrin for ferric ions

 

Reference

Absorption

 

Kd1 (pM)

Kd2 (pM)

A280

Site 1 (%)

A280

Site 2 (%)

Gastrin17

 

267

94

100

223

Gastrin17

Baldwin et al. (2015)

300

85

100

313

Gastrin17SO4

 

83

7,320,000

88

259

Gastrin17PO4

 

14

671,000

98

215

CCK8

Baldwin et al. (2008)

Not detected

   

CCK8SO4

Baldwin et al. (2008)

Not detected

   

CCK8PO4

Baldwin et al. (2008)

Cooperative

Cooperative

 

194a

  1. The affinity of, and the percentage absorbance change at 280 nm on, the binding of the first and second ferric ions to gastrin17, gastrin17SO4 or gastrin17PO4 at pH 4.0 were determined by fitting the mean data obtained in the absorbance experiments (N = 3) described in the Fig. 1 legend to a two site ordered model with the program BioEqs
  2. aThe absorbance changes for CCK8 and its derivatives were measured at 275 nM as the peptide contains tyrosine and phenylalanine, but no tryptophan, residues (Baldwin et al. 2008)