Cysteine facts for kids

Cysteine (pronounced SIS-teen) is a very important amino acid. Think of amino acids as tiny building blocks. Our bodies use these blocks to make proteins. Proteins are super important for almost everything our bodies do, like building muscles and fighting off sickness.

Cysteine is special because it contains sulfur. This sulfur helps it do many important jobs in our bodies. It's often called Cys or C for short.

How Our Body Uses Cysteine

Our bodies can actually make cysteine! This means it's a "semi-essential" amino acid. We don't always have to get it from food, but eating foods rich in cysteine can still be helpful.

Building Strong Proteins

One of cysteine's most important jobs is helping proteins keep their shape. Cysteine molecules can link up with each other using their sulfur parts. This creates a strong connection called a disulfide bond. Imagine two hands holding tightly together! These bonds help proteins fold correctly and stay strong. This is super important for proteins like those in your hair and skin.

Protecting Your Body

Cysteine is also a key part of a powerful molecule called glutathione. Glutathione is like a superhero for your cells! It helps protect them from damage caused by harmful substances called free radicals. This protection is really important for keeping you healthy.

Helping Enzymes Work

Many enzymes in your body need cysteine to work properly. Enzymes are special proteins that speed up chemical reactions. Cysteine's unique structure helps these enzymes do their jobs, like breaking down food or making new molecules.

Where Can We Find Cysteine?

You can find cysteine in many foods. It's especially common in foods that are high in protein.

Cysteine in Food

Some good sources of cysteine include:

• Meat (like chicken and beef)
• Eggs
• Dairy products (like milk and cheese)
• Legumes (like lentils and beans)
• Whole grains

Cysteine as a Food Additive

Sometimes, cysteine is added to foods. When it's used as a food additive, it has a special code called E920. It can be used in things like bread dough to make it stronger and more elastic.

Images for kids

• 

  (R)-Cysteine (left) and (S)-Cysteine (right) in zwitterionic form at neutral pH

• 

  Cystine (shown here in its neutral form), two cysteines bound together by a disulfide bond

Quick facts for kids L-Cysteine
IUPAC name	Cysteine
Other names	2-Amino-3-sulfhydrylpropanoic acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

See also

In Spanish: Cisteína para niños