Hi Joni, I'm not in a position to answer this question, but will note what you and others on this list may already know. Rubisco is an enzyme that helps plants convert CO2 into useful carbon. It may be the most abundant enzyme on earth?
https://en.wikipedia.org/wiki/RuBisCO
According to information cited in the above-linked article, "RuBisCO is the most abundant protein in leaves, accounting for 50% of soluble leaf protein in C3 plants (20–30% of total leaf nitrogen) and 30% of soluble leaf protein in C4 plants (5–9% of total leaf nitrogen)." Of course, millets, including sorghum, are C4 plants.
BTW, the camel-case rendition of RuBisCo made the name look like a spin-off of NaBisCo (Rubicon Biscuit Co.?).
HTH,