Process for cognate nucleotide detection in a nucleic acid sequencing workflow

A method of identifying cognate nucleotides for each of a plurality of nucleic acid features, each feature comprising a primed template nucleic acid molecule, said method comprising the steps of:

• (a) preparing first stabilized ternary complexes at each of the plurality of nucleic acid features, each stabilized ternary complex comprising the primed template nucleic acid molecule at its respective nucleic acid feature, a reversible terminator nucleotide, and a polymerase;
• (b) contacting the first stabilized ternary complexes from step (a) with a reagent comprising a catalytic metal ion, at least one distinguishably labeled incorporable nucleotide, and a polymerase, to produce a reaction mixture,
• whereby the reversible terminator nucleotide incorporates into the primed template nucleic acid molecule to produce a blocked primed template nucleic acid molecule at each of the plurality of nucleic acid features, and
• whereby there forms at each of the plurality of nucleic acid features a second stabilized ternary complex comprising the blocked primed template nucleic acid molecule and one of the distinguishably labeled incorporable nucleotides;
• and
• (c) identifying cognate nucleotides for the primed template nucleic acid molecules at each of the plurality of nucleic acid features by detecting, in the reaction mixture, a label joined to the distinguishably labeled incorporable nucleotide of the second stabilized ternary complex.