Lactoglobulin amino acid sequence

FIGURE 10.27 3-Lactoglobulin-amino acid sequence. May be replaced by other amino acids in genetic variants. Few, if any residues are phosphorylated. 

Preaux, G., Braunitzer, G., Schrank, B. and Stangl, A. 1979. The amino acid sequence of goat d-lactoglobulin. Hoppe-Seyler s Z. Physiol. Chem. 360S, 1595-1604 (German). 

About 20% of milk protein is soluble in the aqueous phase of milk. These serum proteins are primarily a mixture of /3-lactoglobulin, a-lactalbumin, bovine serum albumin, and immunoglobulins. Each of these globular proteins has a unique set of characteristics as a result of its amino acid sequence (Swaisgood 1982). As a group, they are more heat sensitive and less calcium sensitive than caseins (Kinsella 1984). Some of these characteristics (Table 11.1) cause large differences in susceptibility to denaturation (de Wit and Klarenbeek 1984). 

Figure 4.22 Amino acid sequence of bovine -lactoglobulin, showing amino acid substitutions in genetic polymorphs and the intramolecular disulphide bonds (, ---) (from Swaisgood,...

The specific sequence of amino acids in a protein determines its structure, conformation, and physicochemical properties. The structure of protein is categorized as primary, secondary, tertiary, or quaternary, depending on the progressive state of spatial arrangement of polypeptide chains of the protein (1,2). Although the primary structures of almost all major food proteins are known, the exact conformation of only a few native proteins e.g. 9-lactoglobulin has been elucidated (3-5). 

Table 10.9 shows the corresponding changes in the amino acid composition of P-lactoglobulin. The monomeric P-lactoglobulin has a molecular weight of ISkdal and consists of 162 amino acids, whose sequence is shown in Table 10.8. It exhibits a reversible, pH-dependent oligomerization, as represented by the equation ...

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