Npgrj_nmeth_821 35..40

Photochemical uncaging of bio-active molecules was introduced in 1977, but since then, there has been no substantial improvement in the properties of generic caging chromophores. We have developed a new chromophore, nitrodibenzofuran (NDBF) for ultra-efficient uncaging of second messengers inside cells. Photolysis of a NDBF derivative of EGTA (caged calcium) is about 16–160 times more efficient than photolysis of the most widely used caged compounds (the quantum yield of photolysis is 0.7 and the extinction coefficient is 18,400 M–1 cm–1). Ultraviolet (UV)-laser photolysis of NDBF-EGTA:Ca2+ rapidly released Ca2+ (rate of 20,000 s–1) and initiated contraction of skinned guinea pig cardiac muscle. NDBF-EGTA has a two-photon cross-section of B0.6 GM and two-photon photolysis induced localized Ca2+-induced Ca2+ release from the sarcoplasmic recticulum of intact cardiac myocytes. Thus, the NDBF chromophore has great promise as a generic and photochemically efficient protecting group for both oneand two-photon uncaging in living cells.