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Query: EC:3.5.4.4 (
adenosine deaminase
)
5,136
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The effects of the adenosine receptor agonists (-)-N6-phenylisopropyladenosine (PIA) and 5'-N-ethylcarboxamideadenosine (NECA) on the force of contraction, adenylate cyclase activity and cAMP content in the presence of isoprenaline (Iso) were studied in ventricular preparations of the guinea-pig heart. Only in the presence of
adenosine deaminase
(
ADA
) and 50 mM
sodium chloride
, i.e. under 'optimal' conditions, did PIA and NECA reduce the Iso-stimulated adenylate cyclase activity in broken cell preparations, with a maximal effect of about 25%. In electrically driven (1 Hz) papillary muscles from guinea-pigs, both compounds concentration dependently reduced the Iso-stimulated force of contraction maximally by about 50% in the presence of
ADA
(1 microgram/ml). cAMP was measured in the same preparations. Low concentrations (0.1-1 microM) of PIA reduced the cyclic AMP content while higher concentrations increased the cyclic AMP content. The negative inotropic effect of NECA was accompanied by a concentration-dependent increase in the cyclic AMP content. We conclude that the negative inotropic effect of PIA in the presence of Iso is only in part due to a decrease in the cyclic AMP content resulting from inhibition of adenylate cyclase activity. Such an effect was only detected in the presence of
ADA
so that endogenous adenosine can obviously mask small effects of PIA on adenylate cyclase activity or the cyclic AMP content. In addition, the negative inotropic effect of NECA in the presence of isoprenaline was not accompanied by a reduction but an increase in the cyclic AMP content.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Effects of adenosine analogues on force and cAMP in the heart. Influence of adenosine deaminase. 254 33
Theophylline inhibits basal adenylate cyclase activity as well as cyclase stimulated by
sodium chloride
, sodium fluoride, GTP or 5'-guanylimidodiphosphate. This inhibition, is dose-dependent and shows non-competitive inhibition, with respect to MgATP. The presence of
adenosine deaminase
does not alter the effect of theophylline. The inhibition produced by theophylline is not additive with that due to 2'-deoxyadenosine 3'-monophosphate (a P-site agonist). It is suggested that theophylline may act at the P-site to reduce adenylate cyclase activity.
...
PMID:Inhibition of rabbit cardiac adenylate cyclase by theophylline. 286 8
Effects of sodium dodecyl sulfate, dodecyltrimethylammonium bromide,
sodium chloride
, sodium sulfate, methanol and ethanol, on the structure and activity of
adenosine deaminase
(
ADA
) were investigated by UV-Vis, circular dichroism spectrophotometry and molecular dynamics (MDs) studies. Relative activity, experimental and computational helix content, total accessible surface area (ASA) and exposed charged surface area (ECSA) were obtained. The relative activity of
ADA
in the absence and the presence of denaturants were compared with structural results. It was shown that an increase in the surface area and a decrease in the amount of helicity are associated with a decrease in the activity of
ADA
.
...
PMID:Effects of surfactant, salt and solvent on the structure and activity of adenosine deaminase: molecular dynamic and spectrophotometric studies. 1849 40
