We have built a fluorescence correlation spectroscopy (FCS) microscope for ultraviolet excitation (280 300 nm) and emission. With UV excitation the fluorescence of natural fluorophores such as the modified nucleotide 2-aminopurine can be analyzed. The sensitivity of a natural fluorophore toward conformational changes can reveal dynamics in biomolecules. UVFCS is well suited for detection of intensity fluctuations related to such conformational dynamics. Here we show UVFCS measured on pQuarterphenyl and on 2-aminopurine (2-AP). The triplet state rate constants and the excitation cross section for 2- AP were estimated to k[23]=1 x 10[6] s[-1], k[31]=3 x 10[5] s[-1], and ?=2 x 10[-17] cm[2].
Print ISSN: 1431-6730
Volume: 382, 03/2001
Pages: 393 - 397