Cystine

An Amino Acid

Description:

Cystine is formed by 2 cysteine molecules that have lost their hydrogens. The molecules are connected by a disulfide bond. Some authorities do not consider cystine an amino acid because it is a product of an oxidation between the thiol side chains of two cysteine amino acids.

Plants/Foods:

• Avocado
• Cheese
• Chicken
• Chocolate
• Cottage cheese
• Duck
• Egg
• Granola
• Oat flakes
• Pork
• Ricotta
• Turkey
• Wheat germ
• Whole milk
• Wild game
• Yogurt

Physiologic Functions:

• Breaks down mucus deposits
• Contributes to the structure of proteins by holding them in shape
• Contributes to the form and mechanical properties of proteins
• Found in hair keratin, insulin, and certain digestive enzymes, chromotrypsinogen A, papain and trypsinogen
• Needed by the body for proper utilization of vitamin B6
• Stabilizes tertiary structure of certain macromolecules

Clinical Indications:

• Bronchitis
• Burns
• Cystic fibrosis
• Kidney stone prevention
• Protection against alcohol intake by preventing liver damage
• Protection against cigarette smoke
• Protection against radiation effects

Signs and Symptoms of Deficiency:

• Limited data

Causes of Deficiencies:

• Limited data

Contraindications:

• Cystinosis
• Fanconi's syndrome
• Renal lithiasis due to increased cystine in the body

Toxicity and Side Effects:

• A build-up of cystine can occur-see contraindications

Copyright 1998 - 2008 by L. Vicky Crouse, ND and James S. Reiley, ND. All rights reserved (ISSN 1527-0661).