Thermolysin calcium-binding sites

In addition, peptides binding different minerals have been found in whey proteins, i.e., from (3-lg, a-la and LF. Since these proteins are not phosphorylated, the minerals seem to bind through other binding sites than caseins. Seventeen (17) different peptides have been identified by hydrolysis of (3-lg with thermolysin using two different concentrations of calcium. Also, peptides from a-la and LF using trypsin, chymotrypsin or pepsin have been reported. Studies with 3-lg and a-la peptides have shown a higher affinity for iron than the native proteins (Vegarud et al., 2000). 

Figure 7. The structure of thermolysin. Ribbon representation of the structure of thermolysin (silver, Brookhaven Databank [53] code 3TLN) shown with a bound inhibitor (green). The catalytic zinc atom (cyan) and structural calcium atoms (magenta) are shown. The active site is located between the N-terminal zinc protease domain and the alpha helical C-terminal domain. Zinc binding residues are in blue and the residue assisting catalysis is shown in red.

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