Adenosine Deaminase in Chicken‐Egg Yolk and Its Relation to Homologous Enzymes in Liver and Plasma of the Adult Hen

Abstract

Chicken egg yolk contains an adenosine deaminase that was investigated after purifying about 500 times. It has a pH optimum at 6.5, a K , of 6.6 x lo-' mol/l and an approximate molecular weight of 14000; higher molecular forms could not be detected. It was compared with the adenosine deaminases of chicken liver and blood plasma. From this comparison it is evident that this protein has undergone certain changes during the successive events leading to its final structure (secretion by the liver, transport through blood plasma to the oocytes and development of the egg) : a common subunit with an approximate molecular weight of 15 000 may be the basis of the physiological diversifications. Substrate specificity of the purified extracts extends to cytidine and guanosine also, although certain observations point to different enzymes being involved. Deoxyadenosine is also deaminated. Cu2+, Zn2+ and Pb2+ are inhibiting and free-SH seems essential for activity.

Adenosine deaminase from camel tick Hyalomma dromedarii: purification and characterization

“…This was supported by the inhibition of metal ions on adenosine deaminase for chicken eggs (De Boeck et al 1975), Camel skeletal muscle (Alrokayan 2002). However, Many reports reported that the effect of metal ions were not inhibited adenosine deaminase from other sources (Minato et al 1965;Aikawa 1966;Pfrogner 1967).…”

A Purine N(1)-C(6) Hydrolase Activity in the Chicken Egg Yolk: a Vestigial Enzyme?

“…Our investiga tions have shown that after their secretion they may be modified at least in some cases. We noticed differences in the enzyme adenosine deaminase isolated from liver, blood plasma and yolk (9). Cholinesterase (EC 3.1.1.8) activities in plasma and in yolk show a different behav iour, too (12).…”

“…It might be mentioned here that xanthine as well as uric acid, 6,8-dihydroxypurine and hypoxan thine are usual constituents of the egg (8, 10). From this and earlier publications (9,11,13, that it is found outside the embryo proper does 23,24,29) we propose the following scheme not mean that it would not be involved in for the degradation of the egg ribonucleic acids: embryogenesis. The fact that purine degrada tion leads to products that are different in the embryo itself and in the medium wherein it develops does not seem to be without a signifi cance.…”

“…Adenosine deaminase activities were determined according to Kalckar (19) or by determinations of the released ammonia (9). Xanthine oxidase activity was measured with various methods.…”

“…4.4) activities in chicken egg yolk preparations (9): it happened frequently that the absorption changes at 265 nm were much greater than those theoretically possible for the conversion of adenosine to inosine or hypoxanthine. The well-known enzymatic chain of adenosine deaminase (EC 3.5.4.4), nucleosidase (EC 3.2.…”