Proper nouns are usually capitalized – a primary-school lesson that all of us have learned.
Let's look at a substance found in a human body.
Arginine (/ˈɑrɡɪniːn/, abbreviated as Arg or R)1 is an α-amino acid. It was first isolated in 1886
Another one, this time a kind of poison
Solanine – Solanine is a glycoalkaloid poison found in species of the nightshade family (Solanaceae), such as the potato (Solanum tuberosum) and the tomato (Solanum lycopersicum).
Being a healthcare provider, I read several research papers, documents and webpages on enzymes or those sort of substances. They all have name, a proper name but none of those written content ever capitalize them. Why?
I also see some exceptions.
Hemp seeds are high in Arginine, an essential amino acid known to improve heart health and protect from heart disease.
But is it due to the comma there? As the following sentence is introducing what 'Arginine' is? But then, is there any rule that if you define a proper noun in the middle of the sentence, you capitalize its first letter and if you don't, you don't! I don't think so. 🙂
Best Answer
These names are usually formed according to some kind of system. Especially in chemistry "new" compounds are often named like that. Even a common word like alcohol gives rise to -ol compounds (like methanol) to indicate to a scientist that the two have certain chemical properties.
The compounds they name may or may not be in common use as nouns, and as such have lost their "name"-feeling.
If you want to capitalize arginine, you should, by rights, also capitalize alcohol, methanol and polypropylene. These are "names" given to substances, but they do not function like proper names.
In extremis, if you want to capitalize them, you should capitalize Water as well. It is, after all, the "proper name" given to dihydrogenoxide.
Of course, when a compound is given a trade mark name, it does get capitalized, even if the name seems to be systematically derived. However, if the name becomes very commonly used, it is possible that the trade mark name loses its "proper name" feel again, and we stop capitalizing it again.
Examples of that are Aspirin and Heroin (trademarks of Bayer), which are now written as aspirin and heroin. Something similar happened with nylon and rayon (trademark of duPont) - their Teflon seems to be going the same way.