Why is methionine an essential amino acid

Slices were incubated with 0. Stained brain sections were photographed using an Olympus BX51 microscope Tokyo, Japan coupled to a Micro-publisher 3. The luminance of the incident light and the time of exposure were calibrated to assign pixel values ranging from 0 to in the RGB image no-light to full-light transmission , which were used along all preparations.

The photographs were captured with 20x and 40x objectives. The images were analyzed using theImage-J software NIH to measure the total area occupied by the cortex or hippocampus.

Immunofluorescence in brain slices was performed as described previously [ , ]. Slices were washed three times in ice-cold PBS and then permeabilized for 30 min with 0.

Then, slices were mounted with mounting medium on gelatin-coated slides and analyzed by fluorescence microscopy. Memory flexibility MF tests were performed as previously described [ 50 ].

Briefly, a circular white pool was prepared with non-toxic white paint plus a hidden platform diameter: 9 cm in four quadrants; the animals were pre-trained in this pool for 60 s s , one day before the actual testing began. To acclimate the animals to the room and the swimming strategy, the pool was used without the platform. Then, animals were subjected to testing for 4 consecutive days with a maximum of 15 trials per day.

Every day, the platform position in a quadrant was changed. Testing stopped when the animal reached the platform on three consecutive trials with an average of 20 s s or less.

Data are presented as the number of trials after which animals reached the criteria. Open field OF tests were performed two days after the memory flexibility tests. The animals were individually placed at the center of a 72 x 72 x 32 cm white acrylic boxand left to freely move within it for 10 min. Novel object recognition NOR tests were performed a day after the OF test in a 38 x 38 x 32 cm white acrylic box [ ]. Animals were pre-trained to habituate to the box for two consecutive days, without objects present.

For testing, animals were placed individually at the center of the box in the presence of two identical objects old objects for 10 min.

The animal was later after 2 h exposed to one of the old objects and a new object of a different shape and color than the old object, and the box and objects were cleaned again to continue with the next animal. The recognition index was calculated as the time spent exploring the new object divided by the time exploring both objects. Anticoagulant-treated serum samples were obtained from the blood of treated and control mice.

Plasma was separated through centrifugation and sent to Barnafi-Krause Laboratories Santiago, Chile and analyzed. Behavioral data were analyzed using the non-parametric t-test. The impact of dietary methionine restriction on biomarkers of metabolic health. Prog Mol Biol Transl Sci. Methionine residues as endogenous antioxidants in proteins. Methionine residues may protect proteins from critical oxidative damage. Mech Ageing Dev. Cyclic oxidation and reduction of protein methionine residues is an important antioxidant mechanism.

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PLoS One. A specific amyloid-beta protein assembly in the brain impairs memory. Agbas A, Moskovitz J. Curr Signal Transduct Ther. Grimble RF. The effects of sulfur amino acid intake on immune function in humans. Homocysteine and oxidative stress. Methionine , an essential amino acid, is one of the two sulfur-containing amino acids. The side chain is quite hydrophobic and methionine is usually found buried within proteins.

Unlike cysteine, the sulfur of methionine is not highly nucleophilic, although it will react with some electrophilic centers. It is generally not a participant in the covalent chemistry that occurs in the active centers of enzymes. Methionine is an amino acid that produces several important molecules in your body.

These molecules are essential for the proper functioning of your cells. Because of the important molecules it produces, some recommend increasing methionine intake. However, others recommend limiting it due to possible negative side effects. This article will discuss the importance of methionine and whether you need to worry about the amount of it in your diet. Sources and potential side effects are also discussed. Methionine is an amino acid found in many proteins, including the proteins in foods and those found in the tissues and organs of your body.

One of these is its ability to be converted into important sulfur-containing molecules 1. Sulfur-containing molecules have a variety of functions, including the protection of your tissues, modifying your DNA and maintaining proper functioning of your cells 2 , 3.

These important molecules must be made from amino acids that contain sulfur. Of the amino acids used to make proteins in the body, only methionine and cysteine contain sulfur.

Although your body can produce the amino acid cysteine on its own, methionine must come from your diet 4. Additionally, methionine plays a critical role in starting the process of making new proteins inside your cells, something that is continuously occurring as older proteins break down 1. For example, this amino acid starts the process of producing new proteins in your muscles after an exercise session that damages them 1 , 5.

Methionine is a unique amino acid. It contains sulfur and can produce other sulfur-containing molecules in the body. It is also involved in starting protein production in your cells. One of the major roles of methionine in the body is that it can be used to produce other important molecules. It is involved in the production of cysteine, the other sulfur-containing amino acid used to build proteins in the body 1 , 6.

Cysteine can, in turn, create a variety of molecules, including proteins, glutathione and taurine 1. It also plays a role in the metabolism of nutrients in the body and the production of DNA and proteins 2. Taurine has many functions that help maintain the health and proper functioning of your cells 8. SAM participates in many different chemical reactions by transferring part of itself to other molecules, including DNA and proteins 3 , 9.

SAM is also used in the production of creatine , an important molecule for cellular energy 10 , Overall, methionine is directly or indirectly involved in many important processes in the body because of the molecules it can become.

Methionine can convert into several sulfur-containing molecules with important functions, such as glutathione, taurine, SAM and creatine. These molecules are critical for the normal functions of the cells in your body. A diet based on a single plant item will not be adequate, but we no longer worry about pairing proteins such as beans with rice at a single meal. Instead we look at the adequacy of the diet overall throughout the day.

Nutrient digestion and absorption. Medical Physiology. Philadelphia, PA: Elsevier; chap Dietzen DJ.