Adenosine monophosphate (AMP) deaminase was purified from jumbo squid mantle muscle by chromatography in cellulose phosphate, Q-Fast and 5′-AMP sepharose. Specific activity of 2.5 U/mg protein, 4.5% recovery and 133.68 purification fold were obtained at the end of the experiment. SDS-PAGE showed a single band with 87 kDa molecular mass, native PAGE proved a band of 178 kDa, whereas gel filtration detected a 180 kDa protein, suggesting the homodimeric nature of this enzyme, in which subunits are not linked by covalent forces. Isoelectric focusing of this enzyme showed a pI of 5.76, which agrees with pI values of AMP deaminase from other invertebrate organisms. AMP deaminase presented a kinetic sigmoidal plot with Vmax of 1.16 μM/min/mg, Km of 13 mM, Kcat of 3.48 μM.s-1 and a Kcat/Km of 267 (mol/L)-1.s-1. The apparent relative low catalytic activity of jumbo squid muscle AMP deaminase in the absence of positive effectors is similar to that reported for homologous enzymes in other invertebrate organisms.
- AMP deaminase
- Jumbo squid mantle