Ribonucleotides are an important sort of synergistic umami. MSG is an important source of basal umami. How does combining them influence perceptions of flavour?
Ajinomoto, who produce both MSG and disodium ribonucleotides, claim that a mixture of 98% MSG and 2% ribonucleotides has four times the flavour-enhancing effect of the same quantity of pure MSG.
Verdict: Ribonucleotides increase the taste-enhancing effect of MSG.