S-adenosylmethionine SAM and SAH Analog and Antibody

The normal range of SAM concentration in blood, serum, and plasma has not been determined accurately. Due to population, sample handling, pre-treatment, and detection methods, published results have been inconsistent. It has been recently reported that SAM level in human plasma is about 60nM-140 nM as measured by LC-MS/MS method (Klepacki J, Clin Chim Acta, 2013), whereas > 1.5 uM as measured by HPLC (Carolynk K, J. Chromatography, 1997). Even laboratories utilizing similar techniques have reported wide ranges of concentration for healthy patients. The data is, in general, most useful for comparison within the context of the particular studies. In view of the importance of SAM, it is desirable to have an easy and reliable method to measure its concentration in a biological sample. In immunoassays with high quality antibody against SAM, it is certain that the molecule which specifically and sensitively binds to the antibody is SAM. That is to say, specificity makes the detection method more reliable at the least.

Since SAM is an intrinsically unstable molecule, the determination of its concentration in various biological fluids and tissues has been challenging. The current ways to quantifying SAM and SAH are LC, MS, and combinations of MS. HPLC was used but was proven to have obvious advantages.

The basis of LC-MS/MS and HPLC to measure SAM and SAH is not ideal for biologically active and unstable molecules. Therefore, these methods have limitations. These methods are laborious, time consuming and requires expensive equipment. LC-MS/MS is the prevailing method currently yet it has no consideration of biological activity-relevance of the metabolites it detects. Therefore, its usage in measuring SAM or SAH may not be accurate and complete from the biological perspectives. The chemical methods can only detect free form of SAM or SAH excluding any form of SAM or SAH associated with other biomolecules. Just because LC-MS/MS cannot detect from a sample the SAM molecules that falls within that narrow molecular weight specification may not always mean SAM has been totally degraded, disappeared and non-functioning. Furthermore, the SAM standard used in training LC-MS/MS are not the same as the SAM in living cells, yet in technology like LC-MS/MS, the exact same molecule as the one to be measured is required as the standard. Recently, there is a dispute on the GC-MS and LC-MS analytical methods that may not accurately measure metabolites due to unwanted changes caused by manipulation processes including sample extraction, preprocessing and during the measurement (http://cen.acs.org/articles/93/i42/Heated-Dispute-Over-Analytical-Method.html).

A simple, convenient method that does not require costly instrumentation, but take into considerations of boiological finctions such as capability of bingding relevant melecules definitely worths the efforts to indulge into. We are now able to provide all the basic reagents that are needed to quantitatively measure SAM and SAH with immunoassays and help solve technical issues.

Using our products to measure SAM levels in plasma and serum, many clinical studies are made possible to confirm the above statements. Many studies remain there for scientists of different fields worldwide to get into. We believe more and more important findings related to methylation index will come out in the near future.

Considerable research has been conducted in the past regarding the functions of SAM. For example SAM-e, incubated in vitro with human erythrocytes, penetrates the cell membrane and increases ATP within the cell thus restoring the cell shape. SAM-e is clinically useful in many apparently unrelated areas because of its important function in basic metabolic processes. One of its most striking clinical uses is in the treatment of alcoholic liver cirrhosis that, until now, remained medically untreatable. SAM-e has been administered to patients with peripheral occlusive arterial disease and was shown to reduce blood viscosity, chiefly via its effect on erythrocyte deformability.

Sam-e attenuates the damage caused by tumor necrosis factor alpha (TNFα) and can also decrease the amount of TNFα secreted by cells. SAM-e has been studied for its ability to reduce the toxicity associated with administration of cyclosporine A, a powerful immunosuppressor. It has also been studied in patients suffering from migraines and was found to be of benefit.

Pneumocystis pneumonia (PCP) occurs when the host is immunosuppressed. The PCP in humans is associated with advanced HIV disease, severe malnourishment in children, and treatments for cancers, advanced cancers, rheumatic disease, and the prevention of organ transplant rejection (Perez-Leal et al. Am J Respir Cell Mol Biol Vol 45, PP1142-1146, 2011). It is fatal if untreated. Therefore early diagnosis is very important. Studies have been done regarding S-adenosylmethionine (SAM) levels in the diagnosis of Pneumocystis Carinii Pneumonia (PCP) in patients with HIV Infection. Because S-adenosylmethionine is required by Pneumocystis carinii in vitro, Pneumocystis infection depletes plasma SAM of rats and humans, nicotine reduces SAM of guinea pig lungs, and smoking correlates with reduced episodes of Pneumocystis pneumonia (PCP) in AIDS patients. Chronic nicotine treatment increases lung polyamine catabolic/anabolic cycling and/or excretion leading to increased SAM-consuming polyamine biosynthesis and depletion of lung SAM (J. Biological Chemistry 2005; 280(15):15219-15228). Therefore, severely decreased plasma SAM level helps to predict occurrence of PCP in patients with immunocompromised conditions only. The best treatment regimens for PCP should include keep SAM level low since lowered SAM level helps to kill PCP pathogen, whereas, increasing SAM level is recommended for better outcomes of treating other diseases (not PCP) when SAM or methylation index is low.

In alcoholic liver, SAM is reduced whereas SAH and Hcy levels are increased. Two genes (MAT1A and MAT2A) encode for the essential enzyme methionine adenosyltransferase (MAT), which catalyzes the biosynthesis of S-adenosylmethionine (SAMe), the principal methyl donor and, in the liver, a precursor of glutathione. MAT1A is expressed mostly in the liver, whereas MAT2A is widely distributed. MAT2A is induced in the liver during periods of rapid growth and dedifferentiation. In human hepatocellular carcinoma (HCC) MAT1A is replaced by MAT2A. This is important pathogenetically because MAT2A expression is associated with lower SAMe levels and faster growth, whereas exogenous SAMe treatment inhibits growth (Lu, SC et al. Alcoho 35(3):227-34, 2005).