Activation of brain typtophan hydroxylase by a phosphorylating system

✍ Scribed by Thomas W. Lysz; Paul Y. Sze

• Book ID: 102385645
• Publisher: John Wiley and Sons
• Year: 1978
• Tongue: English
• Weight: 408 KB
• Volume: 3
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490030512

✦ Synopsis

A significant activation of tryptophan hydroxylase (TPH) was achieved by the addition of 1 mM ATP and 10 mM MgC12 to 100,OOOg supernatant prepared from mouse midbrain. The activation produced an increase of enzyme activity by 50-70% above control. Cyclic AMP was not a necessary component in the activation as initially suspected; neither was the involvement of a cyclic AMP-dependent protein kinase detected. The enzyme activation by Mg+2-ATP was totally retained after dialysis, thus excluding the possibility of an allosteric effect. In contrast t o the activation, TPH was found t o be sensitive t o inactivation by acid phosphatase, a dephosphorylating enzyme. These findings are consistent with the proposal that the enzyme activation may involve a phosphorylation process. Furthermore, the activation by Mg+*-ATP in the brain preparations was only minimally observed from neonatal mice and could be abolished from adult mice by administration of hydrocortisone. It appears that the phosphorylation process, as postulated here, may be under developmental and hormonal influences.