TY - JOUR
T1 - Detection of a single nucleotide polymorphism in the human α-lactalbumin gene
T2 - Implications for human milk proteins
AU - Chowanadisai, Winyoo
AU - Kelleher, Shannon L.
AU - Nemeth, Jennifer F.
AU - Yachetti, Stephen
AU - Kuhlman, Charles F.
AU - Jackson, Joan G.
AU - Davis, Anne M.
AU - Lien, Eric L.
AU - Lönnerdal, Bo
N1 - Funding Information:
Supported by faculty research grants to B.L. and funds from Wyeth Nutritionals International.
PY - 2005/5
Y1 - 2005/5
N2 - Variability in the protein composition of breast milk has been observed in many women and is believed to be due to natural variation of the human population. Single nucleotide polymorphisms (SNPs) are present throughout the entire human genome, but the impact of this variation on human milk composition and biological activity and infant nutrition and health is unclear. The goals of this study were to characterize a variant of human α-lactalbumin observed in milk from a Filipino population by determining the location of the polymorphism in the amino acid and genomic sequences of α-lactalbumin. Milk and blood samples were collected from 20 Filipino women, and milk samples were collected from an additional 450 women from nine different countries. α-Lactalbumin concentration was measured by high-performance liquid chromatography (HPLC), and milk samples containing the variant form of the protein were identified with both HPLC and mass spectrometry (MS). The molecular weight of the variant form was measured by MS, and the location of the polymorphism was narrowed down by protein reduction, alkylation and trypsin digestion. Genomic DNA was isolated from whole blood, and the polymorphism location and subject genotype were determined by amplifying the entire coding sequence of human α-lactalbumin by PCR, followed by DNA sequencing. Avariant form of α-lactalbumin was observed in HPLC chromatograms, and the difference in molecular weight was determined by MS (wild type = 14,070 Da, variant = 14,056 Da). Protein reduction and digestion narrowed the polymorphism between the 33rd and 77th amino acid of the protein. The genetic polymorphism was identified as adenine to guanine, which translates to a substitution from isoleucine to valine at amino acid 46. The frequency of variation was higher in milk from China, Japan and Philippines, which suggests that this polymorphism is most prevalent in Asia. There are SNPs in the genome for human milk proteins and their implications for protein bioactivity and infant nutrition need to be considered.
AB - Variability in the protein composition of breast milk has been observed in many women and is believed to be due to natural variation of the human population. Single nucleotide polymorphisms (SNPs) are present throughout the entire human genome, but the impact of this variation on human milk composition and biological activity and infant nutrition and health is unclear. The goals of this study were to characterize a variant of human α-lactalbumin observed in milk from a Filipino population by determining the location of the polymorphism in the amino acid and genomic sequences of α-lactalbumin. Milk and blood samples were collected from 20 Filipino women, and milk samples were collected from an additional 450 women from nine different countries. α-Lactalbumin concentration was measured by high-performance liquid chromatography (HPLC), and milk samples containing the variant form of the protein were identified with both HPLC and mass spectrometry (MS). The molecular weight of the variant form was measured by MS, and the location of the polymorphism was narrowed down by protein reduction, alkylation and trypsin digestion. Genomic DNA was isolated from whole blood, and the polymorphism location and subject genotype were determined by amplifying the entire coding sequence of human α-lactalbumin by PCR, followed by DNA sequencing. Avariant form of α-lactalbumin was observed in HPLC chromatograms, and the difference in molecular weight was determined by MS (wild type = 14,070 Da, variant = 14,056 Da). Protein reduction and digestion narrowed the polymorphism between the 33rd and 77th amino acid of the protein. The genetic polymorphism was identified as adenine to guanine, which translates to a substitution from isoleucine to valine at amino acid 46. The frequency of variation was higher in milk from China, Japan and Philippines, which suggests that this polymorphism is most prevalent in Asia. There are SNPs in the genome for human milk proteins and their implications for protein bioactivity and infant nutrition need to be considered.
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U2 - 10.1016/j.jnutbio.2004.12.010
DO - 10.1016/j.jnutbio.2004.12.010
M3 - Article
C2 - 15866226
AN - SCOPUS:22144477203
SN - 0955-2863
VL - 16
SP - 272
EP - 278
JO - Journal of Nutritional Biochemistry
JF - Journal of Nutritional Biochemistry
IS - 5
ER -
