Labeled nucleotide analogs, reaction mixtures, and methods and systems for sequencing

A labeled nucleotide analog comprising:

• a first avidin protein having four subunits, each subunit comprising one biotin binding site;
• a first nucleotide compound, bound to the first avidin protein, the first nucleotide compound comprising a polyphosphate element, a nucleoside element, an optional multivalent central core element, a terminal coupling element, and a nucleotide linker element;
• and
• a first dye-labeled compound, bound to the first avidin protein;
• wherein the first dye-labeled compound is a compound of structural formula (IIIG):
• wherein
• each L′ is independently a dye compound linker element;
• each S is independently a shield element;
• each Dye is independently either an acceptor dye or a donor dye;
• each B″ is independently a terminal coupling element;
• each p is independently 0 or 1;
• and
• each r″ is independently an integer from 0 to 8;
• s is an integer from 1 to 6;
• and
• t is 0 or 1;
• wherein the compound of structural formula (IIIG) comprises at least one shield element,
• at least one acceptor dye, and at least one donor dye;
• and
• wherein the at least one shield element does not comprise a protein.