Changes in a-Lactalbumin, Total Lactose, UDP-Galactose Hydrolase and other Factors in Tammar Wallaby (Macropus eugenii) Milk during Lactation

Abstract

a-Lactalbumin was isolated from milk of M. eugenii and its concentration in milk samples taken at various times during lactation (0-40 we.eks post partum) was determined by single radial immunodiffusion using rabbit antiserum to the purified protein. The a-lactalbumin concentration remained almost constant throughout lactation even though the concentration of total lactose (free ·lactose plus lactose contained in oligosaccharides) feli to zero after 34 weeks post partum. This fall in lactose was accompanied by a rise in the free galactose and glucose concentrations and marked increases in UDPgalactose hydrolase, nucleotide pyrophosphatase, alkaline phosphatase and acid fj-galactosidase activities. It is suggested that the in vitro hydrolysis of UDP-galactose was due to nucleotide pyrophosphatase and that this enzyme may also playa role in vivo late in lactation by making UDP-galactose unavailable for the synthesis of lactose. Alternatively, lactose and lactose-containing oligosaccharides might be degraded by the acid fj-galactosidase during or after secretion.