title: Pig beta-lactoglobulin I (Sus scrofa domestica, Artiodactyla). The primary structure of the major component.
abstract: beta-Lactoglobulins from pooled milk (Sus scrofa domestica) are isolated and characterized. The complete primary structure of the major beta-lactoglobulin component I is presented. The amino-acid sequence was elucidated by automated Edman degradation of tryptic peptides and cyanogen bromide cleavage products in a liquid phase sequencer. The tryptic and cyanogen bromide peptides were separated by reverse-phase (RP-2) or size exclusion (TSK 2000 SW) high performance liquid chromatography. Pig beta-lactoglobulin is composed of only 159 amino acids in contrast to other beta-lactoglobulins which contain 162 or 166 amino acids. Sequence alignment with previously sequenced beta-lactoglobulins was obtained by introducing two gaps at positions 115 and 151-152. Thus bovine beta-lactoglobulin A reveals 62 amino-acid substitutions. The phylogenetic distance from horse beta-lactoglobulin I and II is indicated by 49.4% and 62% amino-acid exchanges, respectively. Pig beta-lactoglobulin is a mixture of two chains with Gln or Thr at position 119. The free thiol group is localized at position 59. The structural and functional aspects of beta-lactoglobulins and its role in vitamin A (retinol) transport are discussed.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003488:Cyanogen Bromide; D005260:Female; D006736:Horses; D007782:Lactoglobulins / Q000302:isolation & purification; D008892:Milk; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D011247:Pregnancy; D013045:Species Specificity; D013552:Swine; D014357:Trypsin
chemical_list: D007782:Lactoglobulins; D010446:Peptide Fragments; D014357:Trypsin; D003488:Cyanogen Bromide