AMP-deaminase from hen stomach smooth muscle--physico-chemical properties of the enzyme.
AMP-deaminase from hen stomach smooth muscle was isolated and physico-chemical properties of the purified enzyme were investigated. The enzyme had an activity optimum at pH 6.5, and poorly deaminated the substrate analogues tested. At optimum pH (6.5), in the absence of regulatory ligands (control conditions), the enzyme manifested hyperbolic substrate-saturation kinetics with half-saturation constant (S(0.5)) of about 4.5 mM. Additions of adenine nucleotide effectors (ATP, ADP) activated the enzyme strongly at all the concentrations tested, diminishing significantly the value of S(0.5) constant. In contrast, the regulatory effect of orthophosphate was variable, and depended on the orthophosphate concentration used. The molecular mass of the enzyme subunit determined in SDS/PAG electrophoresis was about of 37kDa. The obtained results suggest that in different types of hen muscle, similarly as in humans and rats, expression of AMP-deaminase is under the control of independent genes.
Swieca
Anna
A
Department of Biochemistry, Medical University of Gdansk, Gdańsk, Poland. aswiec@amg.gda.pl
Rybakowska
Iwona
I
Koryziak
Anna
A
Klimek
Jerzy
J
Kaletha
Krystian
K
D000659:AMP Deaminase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002645:Chickens; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009130:Muscle, Smooth / Q000201:enzymology*; D051381:Rats; D013270:Stomach / Q000201:enzymology*
D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000659:AMP Deaminase