Molecular probes are useful for both studying and controlling the functions
of enzymes and other proteins. The most useful probes have high affinity
for their target, along with small size and resistance to degradation. Here,
we report on new surrogates for nucleic acids that fulfill these criteria.
Novel properties of the primer independent synthesis of
poly(A), catalyzed by the yeast poly(A) polymerase are
presented.The commercial enzyme fromyeast, incontrast to
theenzymefromEscherichia coli, is unable to adenylate the
3¢-OH end of nucleosides, nucleotides or dinucleoside poly-phosphates (NpnN).
Adenosine 5¢-polyphosphates have been identified in vitro, as products of
certain enzymatic reactions, andin vivo. Although the biological role of these
compounds is not known, there exist highly specific hydrolases that degrade
nucleoside 5¢-polyphosphates into the corresponding nucleoside 5¢-triphos-phates.
Dinucleoside polyphosphates (NpnN¢s; where N and N¢ are nucleosides
andn= 3–6 phosphate residues) are naturally occurring compounds that
may act as signaling molecules. One of the most successful approaches to
understand their biological functions has been through the use of NpnN¢