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  • Title: Polyamines alter the substrate preference of nuclear protein kinase NII.
    Author: Hara T, Endo H.
    Journal: Biochemistry; 1982 May 25; 21(11):2632-7. PubMed ID: 7093212.
    Abstract:
    When investigating the effects of polyamines on substrate specificity of adenosine cyclic 3', 5'-monophosphate (cAMP) independent nuclear protein kinase NII, we found that the substrate preference of NII was drastically altered in the presence of polyamines. When casein was used as a substrate, spermine stimulated the enzyme activity 7.3-fold at 2 mM, and a 6.5-fold stimulation was observed with 6 mM spermidine. Putrescine was also slightly effective at higher concentrations. With phosvitin as the substrate, however, 2 mM spermine and 4 mM spermidine strongly inhibited the activity by 93% and 80%, respectively, while putrescine showed a weak stimulatory effect. Steady-state kinetics and binding studies suggested that both stimulatory and inhibitory effects of polyamines on NII enzyme activity are probably due to substrate protein-polyamine interactions. The circular dichroism spectrum of phosvitin was apparently altered by spermine, whereas no significant change was observed with casein.
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