Sulfur Containing Amino Acids Cysteine and Methionine

Methionine is nonpolar, but cysteine is polar. Cysteine can form weak hydrogen bonds with oxygen and nitrogen; it is also weakly acidic and is sometimes found at the active site of enzymes. Cysteine also acts as a reducing agent within the cell, both as the free amino acid and in the form of the antioxidant tripeptide glutathione. The sulfydril groups of two cysteine residues can be oxidized to form the double amino acid cystine, and this is the predominant form of the amino acid in extracellular fluid. When the same reaction occurs between cysteine residues in adjacent polypeptide chains, a strong, covalent disulfide bond is formed that gives the protein a rigid structure. This appears to be particularly important in stabilizing extracellular or secreted proteins. Methionine can be converted to S-adenosyl-methionine, the donor of methyl groups in transmethylation reactions. Methionine can be converted to cysteine in the body, but not vice versa. Selenium can replace sulfur in some cysteine and methionine residues, particularly when selenium intake is high. The antioxidant protein glutathione peroxidase requires a selenocysteine residue at its active site.

Supplements For Diabetics

Supplements For Diabetics

All you need is a proper diet of fresh fruits and vegetables and get plenty of exercise and you'll be fine. Ever heard those words from your doctor? If that's all heshe recommends then you're missing out an important ingredient for health that he's not telling you. Fact is that you can adhere to the strictest diet, watch everything you eat and get the exercise of amarathon runner and still come down with diabetic complications. Diet, exercise and standard drug treatments simply aren't enough to help keep your diabetes under control.

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