Polypeptide chain, transferrins folding

Polyoxygen fluoride radicals, 16 115 Polypeptide chain, transferrins, 41 397-398 folding, 41 400-402, 417-418 Polypeptide folding, iron-sulfur proteins, 47 271-276... 

All transferrins characterized so far consist of a single polypeptide chain of 670-700 amino acid residues. The lactoferrin and serum transferrin structure analyses show that the folding (polypeptide chain conformation) is the same in both proteins and, given their sequence homology, can be assumed to hold for all proteins of the transferrin family. 

The polypeptide chain is first of all folded into two globular lobes, representing the N-terminal and C-terminal halves of the molecule these are referred to as the N-lobe and C-lobe, respectively. In human lactoferrin the N-lobe comprises residues 1-333 and the C-lobe, residues 345-691, whereas in rabbit serum transferrin the equivalent lobes comprise 1-328 and 342-676. Each lobe contains a single iron binding site, and each has essentially the same folding (described more fully in Section III.B.2). The two lobes do not have equivalent orientations... 

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