ABSTRACT
The detailed nature of the conformational change in transferrins has been defined in the crystal structure of apolactoferrin [78], where a domain rotation of 54° gives rise to an open N-lobe binding cleft; this depends on a hinge movement in two antiparallel polypeptide strands that pass behind the iron site, which allows one domain to move as a rigid body relative to the other [143]. There are, however, distinct structural and functional differences between lactoferrin and transferrin, in particular the fact that transferrin releases iron from its N lobe at a distinctly higher pH than lactoferrin (5.5, compared with 3.0). Amino acid substitutions may also influence the conformational change [144].
