BSA - Bovine Serum Albumin (Bos d 6)

Allergen Data Collection: Beef (Bos domesticus)
Internet Symposium on Food Allergens 3(4):171-84 (2001) [http://www.food-allergens.de]

7.4 Properties of Bovine Serum Albumin

7.4.1 Molecular Biological Properties

Bovine Serum Albumin (BSA) References

Allergen Nomenclature Bos d 6 (1) Allergen Nomenclature Sub-Committee 2001

Molecular Mass
Mr in SDS-PAGE: 67.0 kDa (1), 66.3 kDa (2)
Mr (calculated): 66.4 kDa (precursor, 3) (1) Miller & Gemeiner 1993
(2) Wal 1998
(3) SWISS-PROT

Isoelectric Point pI 4.7-4.95 (1), 4.9-5.1 (2)
(1) Miller & Gemeiner 1993
(2) Wal 1998

Amino Acid Sequence, mRNA, and cDNA

BSA

SWISS-PROT: P02769

GenBank: M73993, X58989, Y17769

PIR: ABBOS

Amino acids 583 residues (1), 607 (precursor)

mRNA 2035 bp, 2061 bp, 1883 bp

cDNA

(1) Brown 1975

Posttranslational Modifications
Disulfide Bridges:
9 disulfide bonds (1) (1) Brown 1974

Biological Function
BSA belongs to the ALB/AFP/VDB family, main plasma protein (1)
3 homologous domains: I aa 4-177, II aa 196-369, III aa 388-567 (on precursor: I aa 28-201, II aa 220-393, III aa 412-591 (1)
good binding capacity for water, Ca2+, Na+, K+, fatty acids, hormones, bilirubin and drugs, main function regulation of colloidal osmotic blood pressure (1) (1) SWISS-PROT

Location
production in plasma, extracellular secretion (1) (1) SWISS-PROT

Sequence Homology
serum albumin from sheep: aa sequence identity 92% (1)
serum albumins from pig, cat, human, rhesus macaque, horse, rabbit: aa sequence identities 72-79% (1) (1) BLAST at PIR

Other Properties
possible trigger of insulin-dependent diabetes mellitus: BSA peptide aa 126-144 (ABBOS) may be the reactive epitope (1) (1) Karjalainen et al. 1992

7.4.2 Allergenic Properties

Bovine Serum Albumin (BSA) References

Frequency of Sensitization
IgE-binding to BSA in 0-88% of patients (1) (1) see 7.1 Sensitization to Beef Allergens

B-Cell Epitopes
IgE binding sites located on aa sequence of BSA:
aa 500-574 (of BSA) / aa 524-598 (of precursor) (1)
(1) tryptic peptides, SDS-PAGE immunoblotting, 5 beef allergic children
(1) Beretta et al. 2001

Alteration of Allergenicity
heat treatment:
Negative reaction to cooked BSA (1.8 g) and positive reaction to uncooked BSA (55 mg) in DBPCFC in a 19-year old woman (2)
pepsin hydrolysis:
ABBOS epitope (aa 126-144) not completely eliminated during digestion at pH 3-4 (mAb ELISA inhibition)* (1)
Progressive reduction of positive responses in SPT and RAST after digestion with pepsin (5 min to 1 h) (3)
* no IgE-binding studies
(1) Alting et al. 1997
(2) Kanny et al. 1998
(3) Fiocchi et al. 1995b
see also 10 Stability of Beef Allergens

Bovine Serum Albumin (BSA)	References
*Frequency of Sensitization* IgE-binding to BSA in 0-88% of patients (1)	(1) see 7.1 Sensitization to Beef Allergens
*B-Cell Epitopes* IgE binding sites located on aa sequence of BSA: aa 500-574 (of BSA) / aa 524-598 (of precursor) (1) (1) tryptic peptides, SDS-PAGE immunoblotting, 5 beef allergic children	(1) Beretta et al. 2001
*Alteration of Allergenicity* heat treatment: Negative reaction to cooked BSA (1.8 g) and positive reaction to uncooked BSA (55 mg) in DBPCFC in a 19-year old woman (2) pepsin hydrolysis: ABBOS epitope (aa 126-144) not completely eliminated during digestion at pH 3-4 (mAb ELISA inhibition)* (1) Progressive reduction of positive responses in SPT and RAST after digestion with pepsin (5 min to 1 h) (3) * no IgE-binding studies	(1) Alting et al. 1997 (2) Kanny et al. 1998 (3) Fiocchi et al. 1995b see also 10 Stability of Beef Allergens