E. Ogawa et al., LYSINE AND GLUTAMATE TRANSPORT IN THE ERYTHROCYTES OF COMMON BRUSHTAIL POSSUM, TAMMAR WALLABY AND EASTERN GREY-KANGAROO, Comparative biochemistry and physiology. Part A, Molecular & integrative physiology, 119(4), 1998, pp. 951-956
It was recently coincidentally discovered, using H-1 NMR spectroscopy,
that the erythrocytes of two species of Australian marsupials, Tammar
Wallaby (Macropus eugenii) and Bettong (Bettongia penicillata), conta
in relatively high concentrations of the essential amino acid lysine (
Agar NS, Rae CD, Chapman BE, Kuchel PW. Comp Biochem Physiol 1991;99B:
575-97). Hence, in the present work the rates of transport of lysine i
nto the erythrocytes from the Common Brushtail Possum (Dactylopsila tr
ivirgata) and Eastern Grey Kangaroo (Macropus giganteus) (which both h
ave low lysine concentrations), and Tammar Wallaby were studied, to ex
plore the mechanistic basis of this finding. The concentration-depende
nce of the uptake was studied with lysine alone and in the presence of
arginine, which may be a competitor of the transport in some species.
In relation to GSH metabolism, glutamate uptake was determined in the
presence and absence of Na+. The data was analysed to yield estimates
of the maximal velocity (V-max) and the K-m in each of the species. E
rythrocytes from Tammar Wallaby lacked saturable lysine transport in c
ontrast to the other two species. The glutamate uptake was normal in a
ll three animals for adequate GSH biosynthesis. (C) 1998 Elsevier Scie
nce Inc. All rights reserved.