Adenylate cyclase in the rat pancreas properties and stimulation by hormones

摘要: Abstract 1. In view of evidence for a role cyclic AMP in the secretin-stimulated water and electrolyte secretion pancreozymin-stimulated enzyme by pancreas, occurrence adenylate cyclase pancreas has been investigated. 2. The presence particulate fraction rat demonstrated. Basal activity is very low under standard conditions (less than 3 pmoles/min per mg protein), but 10 mM NaF stimulates to 15–40 protein. 3. Properties have determined NaF. apparent K m ATP, derived from Lineweaver-Burk plot 0.3 mM. At ATP concentrations above 1.5 there substrate inhibition. optimal pH 7.4. requires Mg 2+ its activity, 5 higher giving maximal activity. Ca 0.1 inhibits enzyme. 4. stimulated synthetic secretin preparation (half maximally activating concentration 1.5·10 −8 M) as well purified pancreozymin −6 M). latter activation not due contamination secretin. same 7.4 shows inhibition NaF-stimulated 5. adrenalin analogues, acetylcholine hormones glucagon gastrin (synthetic). 6. Specific (per protein) preparations obtained rats with free access food vivo twice high that starved animals. 7. physiological significance these findings discussed.