Some molecular properties of human seminal transferrin (HSmT) in comparison with human serum transferrin (HSrT).

In this paper we report some structural features of human seminal transferrin (HSmT) in comparison with the homologous protein purified from human serum (HSrT). In particular, the sequence of the first 13 N-terminal amino acids of HSmT shows 12/13 of identity with the first 13 N-terminal amino acids of HSrT, the ninth residue of the former protein being not definitely determined. Moreover, HSrT and HSmT analysed under the same conditions, by means of reversed phase HPLC, thiol groups determination and second derivative spectroscopy, show a different content of amino acids. In particular, HSmT exhibits mainly: i) a lower Asx/Glx ratio; ii) a reduction of about 50% in Cys residues; iii) a decrease of Tyr and Trp residues. Eventually oligosaccharide parallel analyses of HSmT and HSrT show the same glycosidic bond and almost the same sugar content (around 5.5% w/w); conversely, HSmT lacks of sialic acid residues and probably it contains fucose. These results, taken all together, could be sound of interest to a better understanding of the possible physiological roles of HSmT.