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FIZIKA A 17 (2008) 3 , 109-116
 
MEASUREMENT OF THE INTERSYSTEM CROSSING YIELD OF s4U WITHIN tRNA
BY TIME-RESOLVED ABSORPTION BLEACHING
Z. SHAQIRI, D. ANGELOV and E. VIDOLOVA-ANGELOVA
Institute of Solid State Physics, Bulgarian Academy of Sciences,
72, Tsarigradsko Shaussee blvd., 1784 Sofia, Bulgaria
aE-mail address:
evidol@issp.bas.bg
Received 6 March 2008; Accepted 19 November 2008
Online 28 January 2009
The rare base 4-thiouridine (s4U), present in various transfer RNA (tRNA)
molecules from Escherichia coli, occupies usually the strategically important 8th
position between the double helices of the acceptor and the dihydrouridine stems
of the cloverleaf. This unusual base is largely used as an intrinsic build-in
probe for RNA conformational and RNA(DNA)-protein interaction studies through
triplet excited state photochemistry related to covalent adducts formation.
Here, by applying laser transient absorption saturation spectroscopy, we
measured the intersystem crossing yield jST and the excited triplet state
absorption eT-T of s4U within tRNA. While the
incorporation of s4U in tRNA induced appreciable changes in the
latter, no important variation of the intersystem crossing yield was observed,
which is in contrasts with the published data.
PACS numbers: 87.14.Gg, 87.15.Kg
UDC 539.199, 539.196
Keywords: 4-thiouridine (s4U), RNA conformational and RNA(DNA)-protein
interaction, laser transient absorption saturation spectroscopy, intersystem
crossing yield, excited triplet state absorption
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