This is simplified information about 2S seed storage proteins – there are more resources available at the bottom of the page for further reading for those who are interested in knowing more.
What are 2S seed storage proteins?
They are water soluble proteins found in a wide variety of nuts, seeds, fruit and vegetables. As allergenic proteins go, they are very stable, which means they are not easily damaged by extreme changes in temperature or pH due to their small size and compact structure. This means that the proteins ability to trigger and allergic reaction in a sensitised individual would not be hindered by cooking, freezing, digestion or in many cases food processing.
Their function in plants is as a source of nutrients during germination and growth of seedlings. They are also thought to also to play a role in defence against plant pathogens.
2S albumins are a part of the prolamin superfamily; other allergenic proteins included in this superfamily are lipid transfer proteins and prolamin storage proteins of cereals.
What foods are 2S seed storage proteins found in?
In the top 14 foods, peanuts
, brazil nut
, soya beans
all contain 2S seed storage proteins.
Fruits and vegetables containing these proteins are kiwi
and sichuan pepper.
2S seed storage proteins are also found in rapeseed
, castor beans
, mung bean
, sunflower seeds
and pine nuts.
What symptoms can 2S seed storage proteins cause?
Allergy to foods containing 2S seed storage proteins have a wide range of symptoms and severity including urticaria (hives or welts), angioedema (swelling under the skin), nausea, abdominal pain, vomiting or breathlessness and anaphylactic shock.
Are 2S seed storage proteins different from 7S and 11S seed storage proteins?
Many of the foods containing 2S seed storage proteins will also contain 7S seed storage proteins
, also called vicilin and 11S seed storage proteins
, also called legumin. 7S and 11S seed storage proteins are globulins and 2S seed storage proteins are albumins. Globulins are storage proteins found most often in legumes and albumins are water soluble proteins found more often in nuts and seeds.
2S refers to the sedimentation co-efficient of the protein (a measure of how quickly the protein sediments in a centrifuge). These three proteins look similar but they have differing chemical compositions.
A Table of Cross Reactivity between 2S, 7S and 11S seed storage proteins
How Cross Reactive are 2S albumin proteins?
The 2S seed storage proteins in many foods look very similar, but it is not guaranteed that an allergy to one food will result in cross reactivity with another.
There has been shown to be cross reactivity across the Brassicaceae
family, including oilseed rape, turnip rape and mustard.
Please visit the Food Index
of this site if you are interested in the cross reactivity of a specific food, there are lots of resources dedicated to cross reactivity.
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