Abstract

AMP-deaminase from the cardiac muscle of an elasmobranch fish-Thornback ray (Raja clavata) was isolated and physico-chemical properties of the purified enzyme were investigated. At optimum pH (6.6), and in the absence of regulatory ligands (control conditions), AMP-deaminase showed a hyperbolic substrate-saturation kinetics, with half-saturation constant (S0.5) value being about 1.7 mM. Adenine nucleotides (ATP and ADP) activated, while orthophosphate inhibited the activity of Thornback ray fish cardiac muscle AMP-deaminase, influencing mainly the value of S0.5 constant. In contrast to the above, guanine nucleotide (GTP) influenced the enzyme in a more complex way influencing both S0.5 and Vmax values of the reaction. SDS-PAG electrophoresis of Thornback ray fish cardiac muscle AMP-deaminase revealed the presence of two protein fragments of approximate molecular size of 70 and 80 kDa respectively, representing probably different subunit species of the enzyme. Properties of elasmobranch fish Thornback ray cardiac muscle AMP-deaminase presented here were compared with these of teleost fish Raibow trout cardiac muscle AMP-deaminase described previously. The experimental data described here suggest that one gene is responsible for coding AMP-deaminase in the muscles of both elasmobranch and teleost fish.

Adres: prof. dr Krystian Kaletha
Zakład Biochemii i Fizjologii Klinicznej AMG
ul. Dębinki 1, 80-211 Gdańsk
e-mail: kaletakj@mediclub.pl
tel./fax: 58 349-14-65