Primary structure of water buffalo α-lactalbumin variants A and B

• Published in: Journal of dairy research 2004-02, Vol.71 (1), p.14-19
• Main Authors: Chianese, Lina, Caira, Simonetta, Lilla, Sergio, Pizzolongo, Fabiana, Ferranti, Pasquale, Pugliano, Giovanni, Addeo, Francesco
• Format: Article
• Language: English
• Subjects: Alleles; Amino Acid Sequence; amino acid substitution; Animal productions; Animals; Biological and medical sciences; bovine; Buffaloes; Chromatography, High Pressure Liquid; consensus sequence; Fundamental and applied biological sciences. Psychology; Galactosyl transferase; Gene Frequency; Genetic Variation; Glycosylation; Immunoblotting; ionization; Isoelectric Focusing; isoelectric point; lactalbumin; Lactalbumin - chemistry; Lactalbumin - genetics; mass spectrometry; Milk Proteins - chemistry; Molecular Sequence Data; molecular weight; Spectrometry, Mass, Electrospray Ionization; Terrestrial animal productions; Vertebrates; Whey Proteins; β-lactoglobulin
• ISSN: 0022-0299; 1469-7629
• DOI: 10.1017/S0022029903006551

A novel electrophoretic α-lactalbumin (α-la) variant was detected in the Italian water buffalo breed. The isoelectric point of the variant, labelled A, was lower than the most frequent variant B. It presented an allelic frequency of 0·5% compared with the 97·1% of the BB allele. From Liquid Chromatography-Electrospray Ionization/Mass spectrometry, the molecular mass of the two α-la A and B variants were measured as 14235·1±0·8 and 14236·1±0·9 Da, respectively. The two proteins were sequenced and differentiated from one another by a single amino acid substitution, Asn45(B)→Asp45(A). As this amino acid substitution altered the N-glycosylation sequence consensus Asn45–X–Ser46 it may be deduced that the protein glycosylation level of the α-la A would decrease.