NMOC-DBHQ, A NEW CAGED MOLECULE FOR MODULATING SARCOPLASMIC ENDOPLASMIC RETICULUM CA2+ ATPASE ACTIVITY WITH LIGHT-FLASHES/

We report the synthesis and characterization of andelyloxycarbonyl]-2, 5-di(tert-butyl)hydroquinone (Nmoc-DBHQ), a new ''caged'' reagent for photoreleasing DBHQ, a membrane-permeant, reversible inhibitor of the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA). The Nmoc group is a new caging group developed for the current application, Photolys is of Nmoc-DBHQ proceeds with t(1/2) = 126 +/- 2 mu s, and t(1/2) for subsequent release of DBHQ is estimated to be similar to 5 ms. Nmoc-DB HQ thus allows rapid and reversible modulation of SERCA activity in li ving cells. Through its acetoxymethyl ester, Nmoc-DBHQ can be loaded i nto cells easily by incubation. We demonstrate the use of Nmoc DBHQ fo r photomodulating SERCA activity in fibroblasts and vagal sensory neur ons. We further demonstrate the utility of pulsed DBHQ photorelease fo r probing and manipulating dynamic phenomena such as [Ca2+] oscillatio ns in fibroblasts.