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

Abstract
Di(1,N6‐ethenoadenosine) 5′, 5‴‐P1, P4‐tetraphosphate, ϵ‐(Ap4A), a fluorescent analog of Ap4A has been synthesized by reaction of 2‐chloroacetaldehyde with Ap4A. At neutral pH this Ap4A analog presents characteristic maxima at 265 and 274 nm, shoulders at ca 260 and 310 nm and moderate fluorescence (λexc 307 nm, λem 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(Ap4A) and catabolize the resulting ϵ‐nucleotide moieties up to ϵ‐Ado.