Nmoc-DBHQ, a new caged molecule for modulating sarcoplasmic/endoplasmic reticulum Ca2+ ATPase activity with light flashes.

We report the synthesis and characterization of O[o-nitromandelyloxycarbonyl]-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. Photolysis of Nmoc-DBHQ proceeds with t1/2 = 126 +/- 2 micros, and t1/2 for subsequent release of DBHQ is estimated to be approximately 5 ms. Nmoc-DBHQ thus allows rapid and reversible modulation of SERCA activity in living cells. Through its acetoxymethyl ester, Nmoc-DBHQ can be loaded into cells easily by incubation. We demonstrate the use of Nmoc-DBHQ for photomodulating SERCA activity in fibroblasts and vagal sensory neurons. We further demonstrate the utility of pulsed DBHQ photorelease for probing and manipulating dynamic phenomena such as [Ca2+] oscillations in fibroblasts.