Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... The photoactive site of 6-[(4-nitrobenzyl)thio]-9-(β-D-ribofuranosyl)purine, an inhibitor of nucleoside transport across cellular membranes, was studied by radical trapping. Homolytic cleavage of the sulfur-benzyl bond occurred and thiol coupling was observed.