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Detection and characterization by high‐performance liquid chromatography and mass spectrometry of a goat β ‐casein associated with a CSN2 null allele
Author(s) -
Cunsolo Vincenzo,
Galliano Francesco,
Muccilli Vera,
Saletti Rosaria,
Marletta Donata,
Bordonaro Salvatore,
Foti Salvatore
Publication year - 2005
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.2143
Subject(s) - chemistry , chromatography , mass spectrometry , electrospray ionization , tandem mass spectrometry , casein , high performance liquid chromatography , protein mass spectrometry , trypsin , biochemistry , enzyme
Abstract The identification and characterization of a truncated goat β ‐casein, associated with a null β ‐casein allele (CSN2 O′ ), is reported. The truncated β ‐casein predicted at the DNA level (NCBI Acc. No. CAB39313) but never observed at the protein level, here named β ‐casein O, was detected as a minor component in a goat milk sample from an autochthonous breed from southern Italy, ‘Rossa Mediterranea’, by reversed‐phase high‐performance liquid chromatography/electrospray ionization mass spectrometry (RP‐HPLC/ESI‐MS). The ESI mass spectrum of the intact β ‐casein O determined an M r value of 18 780 Da (calculated 18 781.5). Characterization of the amino acid sequence, performed by coupling trypsin digestion with matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS), RP‐HPLC/ESI‐MS and tandem mass spectrometry (MS/MS), demonstrated that the amino acid sequence corresponds to the 1–166 sequence of mature β ‐casein variant A (Acc. No. P33048), thus confirming that the protein is coded by the null allele CSN2 O′ , characterized by a transition (C → T) at the 373rd nucleotide of the 7th exon of the gene, which generates a premature stop codon in position 182. Copyright © 2005 John Wiley & Sons, Ltd.