Di(1,N⁶‐ethenoadenosine)5′, 5‴‐P¹,P⁴‐tetraphosphate, a fluorescent enzymatically active derivative of Ap₄A

Di(1,N 6 ‐ethenoadenosine) 5′, 5‴‐P 1 , P 4 ‐tetraphosphate, ϵ‐(Ap 4 A), a fluorescent analog of Ap 4 A has been synthesized by reaction of 2‐chloroacetaldehyde with Ap 4 A. At neutral pH this Ap 4 A analog presents characteristic maxima at 265 and 274 nm, shoulders at ca 260 and 310 nm and moderate fluorescence (λ exc 307 nm, λ em 410 nm). Enzymatic hydrolysis of the phosphate backbone produced a slight hyperchromic effect but a notorious increase of the fluorescence emission. Cytosolic extracts from adrenochromaffin tissue as well as cultured chromaffin cells were able to split ϵ(Ap 4 A) and catabolize the resulting ϵ‐nucleotide moieties up to ϵ‐Ado.