protein
Pluralproteins (some meanings)
- 1One of the three major classes of food energy, supplying about 4 calories per gram and abundant in meat and some vegetables such as legumes.
Nutritionists recommend balancing protein with carbohydrates and fats at each meal.
A diet too low in protein can lead to muscle loss over time.
Note
On a nutrition label the word becomes a mass noun: you eat protein, get enough protein, or choose foods high in protein. It stands with carbohydrates and fat as the three macronutrients. As Andrea Kane notes, it is the only one of the three that supplies amino acids, which is the link back to the molecule. Put it in the plural, as in "two proteins," and the meaning shifts to a protein-rich food.
- 2Any of many large, complex molecules made of one or more long chains of amino acids linked together by peptide bonds.
Each protein folds into a specific shape that determines its function.
Enzymes are proteins that speed up chemical reactions in the cell.
Note
This is the scientist's sense, the one the name was coined for. Jöns Jacob Berzelius suggested it in a letter to Gerardus Johannes Mulder, building on Greek prōteîos, "primary," from prôtos, "first." In this sense the word is countable (a protein, many proteins) because each molecule is a distinct thing with its own work. As Siddhartha Mukherjee puts it in The Emperor of All Maladies (2010), proteins "carry out the bulk of cellular functions."
- 3A food rich in protein, often a meat or a meat substitute such as tofu or beans.
The chef paired a hearty protein with roasted vegetables.
Vegetarian diets rely on proteins like lentils, tofu, and chickpeas.
Note
Kitchens and menus count what nutritionists measure. Daphne's California Greek catering menu (2017) offers a "choice of 2 proteins & 2 sides," and a diner at a halal cart picks a protein. The word names the main item on the plate, a meat or its substitute, rather than a nutrient inside it. That is why it takes an article and a plural. It belongs to menu and cooking talk, often paired with "sides."
Practice
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Origin
Formed from proto- + -ein, the word was suggested by Jöns Jacob Berzelius in a letter to Gerardus Johannes Mulder. It came from French protéine and German Protein, both coined from Ancient Greek πρωτεῖος (prōteîos, 'primary'), from πρῶτος (prôtos, 'first').