Tag Archives: sulphur

Chronic Liver Disease Shows Amino Acid-Sulphur Deficiency

Turns out that your liver can benefit from the sulphur-containing amino acids methionine and cysteine. Health benefits of amino acids such as these are excellent, but this is especially true for those with liver disease. As it turns out, those with chronic liver disease actually show a pattern of sulphur deficiency, so both cysteine and methionine may help with this.

Advanced liver disease and methionine / cysteine amino acids

In advanced or chronic liver disease, the metabolism of the sulphur-containing aminos, such as methionine and cysteine, are is impaired (no difference in the amino acid taurine, however).

In a study by P Almasio, G Bianchi, et al., at the Clinica Medica R, Università di Palermo, in Italy, the researchers published their discoveries based on 60 people who had chronic liver disease. The results show a pattern of amino acid deficiency in these patients.

10 of the subjects were used a control because they were healthy, but the other 50 patients had chronic liver disease, which was proven via biopsy.

The breakdown of their liver disease impairments

Hypermethioninemia (an extreme amount of methionine) was present in only these cases:

10 cases compensated cirrhosis
10 cases decompensated cirrhosis

Plus there were:

30 cases chronic hepatitis

The results of this clinical trial showed cysteine, a metabolite of methionine metabolism, was “markedly reduced in patients with compensated chronic liver disease, while in advanced cirrhosis its concentration was within the normal range.”

Methionine is an essential amino acid, which means you can only get it through diet, particularly protein foods such as meats (chicken, beef, pork, lamb, plus fish and eggs). Also, cysteine is a non-essential amino acid, which means the body can produce this amino acid on its own. No differences were observed (in plasma levels) for the amino acid taurine between groups.

What was observed was how sulfur-containing amino acid metabolism was deranged and “possibly located at various steps along the trans-sulphuration pathway, is also present in mild forms of chronic liver disease.”

What this means is that a key marker for those with chronic liver disease is that sulphur-containing amino acids are deficient. This can be true for people suffering from decompensated cirrhosis), or hepatitis.

The study did not explain whether supplementing intake with cysteine or methionine would affect the—chronic liver disease–patients in a positive way or not, but it is good to know that both of these amino acids are in ample amounts when associated with healthy livers, yet levels are abnormal in diseased livers.

Reference:

http://www.ncbi.nlm.nih.gov/pubmed/8025302

Sulfur-Containing Amino Acids Cysteine and Methionine

The two main sulfur-containing amino acids are cysteine and methionine; however, there are other sulfur-containing amino acids as well. Both cysteine and methionine are nonpolar as well as hydrophobic, with methionine being extremely hydrophobic as far as amino acids go. Methionine is also found inside proteins, and cysteine is often found there too. There are some other fascinating things about these two (and other) sulfur-containing amino acids.

Aside from methionine and cysteine being most popularly known, other commonly known sulfur-containing amino acids include homocysteine and taurine. The last two are not incorporated into proteins, however. According to the authors at the Journal of Nutrition (JN), the “difference accounts for some of the distinctive properties of the sulfur-containing amino acids. Methionine is the initiating amino acid in the synthesis of virtually all eukaryotic proteins … [and if] exposed, are susceptible to oxidative damage. Cysteine, by virtue of its ability to form disulfide bonds, plays a crucial role in protein structure and in protein-folding pathways.”

The authors of JN discuss a number of these sulfur-containing amino acids—methionine, cysteine, taurine, homocysteine, and the lesser known S-adenosylmethionine.

Importance of sulfur-containing amino acids

Although cysteine and methionine are the primary sulfur-containing amino acids due to being two of the 22 common amino acids that are incorporated within proteins, both taurine and homocysteine are also important for physiological function. So why is sulfur in amino acids since most aminos are made of carbon, oxygen, hydrogen, and nitrogen? Because, says JN, oxygen and sulfur both belong to ‘Group 6’ of the Periodic Table of Elements, so are “capable of making similar covalent linkages” with a critical difference that sulfur has a low electronegativity (oxygen has the second lowest electronegativity). So if oxygen replaces the sulfur it would “result in a much less hydrophobic amino acid.”

Furthermore, substituting oxygen for sulfur—causing oxidation—in sulfur-containing amino acids (including in the more rare S-adenosylmethionine) can have effects in methionine residues where the surface is exposed, causing an oxidation-reduction cycle, imparing the activity of “methionine sulfoxide reductase and the subsequent accumulation of methionine sulfoxide residues [that] are associated with age-related diseases, neurodegeneration, and shorter lifespan.”

Lastly taurine, as one of the more remarkable sulfur-containing amino acids, has very high concentrations within muscle tissues and utilizes a wide variety of functions. Taurine is, says JN, the “most abundant free amino acid in animal tissues [even though it] accounts for only 3% of the free amino acid pool in plasma, it accounts for 25%, 50%, 53%, and 19%, respectively, of this pool in liver, kidney, muscle, and brain.” It is also one of the most necessary sulfur-containing amino acids for cats and results retinal degeneration in kittens if the mothers are not fed a taurine-rich diet. Taurine is also found in human mother’s milk and is added to many infant formulas because it helps with eyesight.

So all in all, sufur-containing amino acids are necessary for proper health of both animals and humans in the proper biological functioning and growth, as well being associated with some diseases and anti-aging and neurological issues.

Reference:

http://jn.nutrition.org/content/136/6/1636S.full