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Syllabification: pro·tein
Pronunciation: /ˈprōˌtēn

Definition of protein in English:


1Any of a class of nitrogenous organic compounds that consist of large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms, especially as structural components of body tissues such as muscle, hair, collagen, etc., and as enzymes and antibodies.
Example sentences
  • The 75-kD fusion protein was purified four times by affinity binding to an amylose resin.
  • Western blot analysis confirmed that this truncated fusion protein is expressed in yeast (data not shown).
  • The scientists have genetically engineered the animals to produce a green fluorescent protein in cells throughout the abdomen.
1.1Proteins collectively, especially as a dietary component: a diet high in protein
More example sentences
  • Some postmenopausal women swear that dietary soy protein combats their hot flushes.
  • Rice is high in protein, but these proteins are low in the essential amino acid lysine.
  • There would be little rice and even less protein for the family before the rains came again in May.


mid 19th century: from French protéine, German Protein, from Greek prōteios 'primary', from prōtos 'first'.



Pronunciation: /ˌprōˌtē(ə)ˈnāSHəs, ˌprōtnˈā-/
Example sentences
  • Transport of polyelectrolytes, in particular of nucleic acid fragments, through proteinaceous pores in membranes has also been reported.
  • They include activated charcoal, Congo red, India ink, proteinaceous compounds and fluorescent materials.
  • Since mitochondria have two membranes, precursors targeted to the matrix must cross both barriers, presumably through proteinaceous channels.

Definition of protein in:

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Word of the day orthoepy
Pronunciation: ˈɔːθəʊɛpi
the correct or accepted pronunciation of words