Structures of Buffalo and Mare Lactoferrins

Abstract

Lactoferrin (Lf), an iron binding glycoprotein found in the external secretions and neutrophilic leucocytes of mammals, is thought to be responsible for primary defence against microbial infection, mainly as a result of lactoferrin sequestration of iron required for microbial growth (Weinberg, 1978). Many other functions have been attributed to lactoferrin, including immunomodulation and cell growth regulation (Lönnerdal & Iyer, 1995). The lactoferrin has molecular mass of 80 kDa. The protein folds into two globular lobes, the N-lobe comprising the N-terminal half of the polypeptide chain and C-lobe comprising the C-terminal half of the polypeptide chain. The lobes are connected by a 3₁₀-helical 10–12 residue peptide. Each lobe is further subdivided into two domains. Each domain contains a single iron binding site, located in the interdomain cleft.