Characterisation of proteins in the milk of fur seals.
Milk protein composition was investigated throughout the lactation periods of the Australian fur seal (Arctocephalus pusillus doriferus) and Antarctic fur seal (Arctocephalus gazella). The mean protein content of the milk was found to be 10.9% and 10.6% respectively. The concentration of total protein did not change during lactation, although a decline in casein content of the milk in late lactation was apparent. Milk protein concentration during a foraging/suckling cycle of the Antarctic fur seal analysed at the time of arrival on shore, and 24 h and 72 h after arrival was 12.8%, 11.4% and 12.5% respectively. Re-feeding animals at 72 h resulted in a significant increase in milk protein content to 14.9%. Characterisation of milk protein by SDS-PAGE analysis revealed 5 casein and 10 major whey protein bands. Amino-terminal sequencing indicated that the majority of the whey fraction of the milk is beta-lactoglobulin (beta-LG). The limited amino acid sequence indicated 3 different beta-LGs were secreted in the milk. Subsequently, RT-PCR was used to extend the sequence of one of the beta-LGs and translation of the 464 bp fragment indicated that it shared 79% sequence identity with feline beta-LG II.
Cane
K N
KN
CRC for Innovative Dairy Products, Department of Zoology, University of Melbourne, Victoria 3010, Australia.
Arnould
J P Y
JP
Nicholas
K R
KR
D000595:Amino Acid Sequence; D000818:Animals; D000833:Animals, Suckling; D002118:Calcium / Q000032:analysis; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004573:Electrolytes / Q000032:analysis; D005260:Female; D046069:Fur Seals / Q000502:physiology*; D005947:Glucose / Q000032:analysis; D007774:Lactation; D007782:Lactoglobulins / Q000235:genetics; D008894:Milk Proteins / Q000032:analysis / Q000737:chemistry*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D000067816:Whey Proteins
D018076:DNA, Complementary; D004573:Electrolytes; D007782:Lactoglobulins; D008894:Milk Proteins; D000067816:Whey Proteins; D005947:Glucose; D002118:Calcium