• Question: what is the weight of a protein?

    Asked by to Sam, Jo on 19 Jun 2014. This question was also asked by .
    • Photo: Sam Lear

      Sam Lear answered on 19 Jun 2014:

      Hi erisl,

      Proteins vary in size between a few thousand and millions of Daltons (Da). A ‘Dalton’ is the unit of weight we use when talking about things on the atomic scale. To give you an idea of how small this is – a single carbon atom has a weight of 12 Da (this is about one hundred thousand million million millionths of a gram!).

      According to Wikipedia, ‘titin’ is the largest known protein. It is found in your muscles and acts like a spring. It contains around 30 000 amino acids and has a weight of nearly 4 million Da. This sounds big but is still only about one hundred thousand million millionths of a gram!

    • Photo: Jo Nettleship

      Jo Nettleship answered on 21 Jun 2014:

      Hi erisl
      As Sam says, proteins come in many different sizes. Lots of proteins also exist as complexes – more than one protein attached to each other. This can either be more than one copy of the same protein – for example antibodies have two copies which are attached to each other in a Y shape to make the entire active protein. Or it can be two different proteins stuck to each other. Here each protein has a different role in the overall activity of the complex.
      Jo

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