Amino acid is any organic compound having a carboxyl functional group (-COOH) and amine (-NH2 usually). In biochemistry often narrowed sense: both are tied to one atom of carbon (C) the same (called atoms C "alpha" or α). Carboxyl group to give the nature of the acid and amine groups provide the alkalinity. In solution, amino acids are amphoteric: tend to be acid in an alkaline solution and a base in acid solution. This behavior occurs because the amino acids could be a zwitter-ion. Amino acid class of compounds including the most studied because of one very important function in the organism, namely as building blocks of protein.
The structure of amino acids in general is one that binds four C atoms cluster: amine group (NH2), carboxyl group (COOH), atomic hydrogen (H), and a residual group (R, of the residue) or also called group or side chain distinguish one amino acid with other amino acids. Central C atoms are named Cα atoms ("C-alpha") in accordance with the naming bergugus carboxyl compounds, namely the C atom which is attached directly to the carboxyl group. Therefore amine group is also bound to the Cα atom, the compound is an α-amino acids. Amino acids are usually classified by the chemical nature of these side chains into four groups. Side chains can make amino acids are weak acids, weak bases, if the polar hydrophilic and hydrophobic if nonpolar. Because of the central C atoms bind four different groups, then the amino acids except glycine, have optical isomers: l and d. A simple way to identify this isomeri of two-dimensional image is to "encourage" H atoms to the reader back (away from the reader). If clockwise (round to the right) occurs carboxyl-residue sequence-amine then this is the type d. If this sequence occurs with anti-clockwise direction of rotation, then it is of type l. (This rule is known in English by the name of Corn, the abbreviation COOH - R - NH 2).
In general, a natural amino acid produced by eukaryotes is of type l although some marine snails produce a type d. Bacterial cell wall contains many amino acids of type d. Proteins are polymers composed of amino acids as a monomer. These monomers are connected by a peptide bond, which binds to the carboxyl group belongs to one monomer with the amine group's next monomer. This splicing reaction (called translation) naturally occurs in the cytoplasm with the help of ribosomes and tRNA. In the polymerization of amino acids, the-OH group which is part of the carboxyl groups and amino acid-H groups that are part of other amino acid amine group will be separated and form water. Therefore, this reaction is included in the dehydration reaction. Amino acid molecule that has been releasing water molecules are said to be named in the form of amino acid residues.
Proteins are composed of various amino acids, each connected by peptide bonds. However, at the beginning of its formation is composed of protein only 20 amino acids known as the basic amino acid or amino acid or amino acid constituent of raw protein (proteinogenik). These amino acids are encoded by a DNA / RNA as the genetic code.
Here are the 20 th amino acid building blocks of protein (abbreviations in parentheses indicate the three-letter abbreviation and single letter is often used in studies of protein).Amino acid is any organic compound having a carboxyl functional group (-COOH) and amine (-NH2 usually). In biochemistry often narrowed sense: both are tied to one atom of carbon (C) the same (called atoms C "alpha" or α). Carboxyl group to give the nature of the acid and amine groups provide the alkalinity. In solution, amino acids are amphoteric: tend to be acid in an alkaline solution and a base in acid solution.
Essential amino acids are amino acids that can not be produced by the body, so it must be obtained from food consumption. Non-essential amino acid is an amino acid that can diprosuksi by the body, so it has a priority lower consumption compared with essential amino acids. Conditionally essential amino acids are a group of non-essential amino acids, but at certain times, like after a hard weight training, production in the body is not as fast and not as much as necessary and should be obtained from food or protein supplements
essential amino acids:
1. Leucine (BCAA = Branched-Chain Amino Acids = branched-chain amino acids)
- Helps prevent muscle contraction
- Helps restore the skin and bones
2. Isoleucine (BCAA = Branched-Chain Amino Acids = branched-chain amino acids)
- Helps prevent muscle contraction
- Assist in the formation of red blood cells
3. Valine (BCAA = Branched-Chain Amino Acids = branched-chain amino acids)
- Not processed in the liver, and more directly absorbed by the muscle
- Help in sending other amino acids (tryptophan, phenylalanine, tyrosine) to the brain
4. Lycine
- Lack lycine will affect the manufacture of proteins in muscle and other tissues
- Together with Vitamin C to form L-Carnitine
- Assist in the formation of collagen and other connective tissues of the body (cartilage and joints)
5. Tyyptophan
- Triggers serotonin (a hormone that has a relaxing effect)
- Stimulate the release of growth hormone
6. Methionine
- Precursor of cysteine and creatine
- Lowering blood cholesterol levels
- Helps to get rid of toxic substances in the liver and membantuk regeneration of new tissue in the liver and kidneys
7. Threonine
- One amino acid that helps detoxify
- Helps prevent fatty buildup in the liver
- An important component of collagen
- Usually the drawbacks suffered by vegetarians
8. Phenylalanine
- Precursor to tyrosine
- Improve memory, mood, mental focus
- Used in the treatment of depression
- Membantuk suppress appetite
PROTEIN
protein is a food substance that is essential for the body because this substance serves as a source of energy in the body as well as builder dn regulator substances. Protein tends to be a polymer of amino acids linked by peptide bonds. Molecule protein-umsur contain elements C, H, O, N, P, S, and sometimes contain metals such as iron and copper (Winarno, 1992). Protein is a polypeptide with a highly varied BM from 5000 served until more than one million because of a large protein molecule, a protein highly susceptible to changes in physical and biological activity. Many agents that cause changes in the nature of proteins such as heat, acids, bases, organic solvents, salts, heavy metals, radioactive radiation (Sudarmadji, 1996)
The structure of amino acids is described as follows :
If the water-soluble amino acids, carboxylic group will release H + ions, whereas the amine group will receive ma H + ions, such as
the following reaction:
By the second cluster, amino acids in solution can form positively charged ions and negatively charged or called amphoteric ion (zwitterion). Ion state is highly dependent on pH. If the amino acids in water coupled with a base, then the amino acids present in the form of (I) because the concentration of OH-ions are capable of binding high H + ions on the-NH3 +. Conversely when added acid to the amino acid solution, the concentration of H + ions can bind with high ion-COO-to form-COOH group of amino acids so that there will be in the form of (II) (Anna Poedjiadi, 1994).
In an electrophoresis system that has a positive and negative electrodes, an amino acid will move toward the electrode opposite to the charge contained amino acids in solution. If the amino acid ions do not move toward the negative and positive in the pH of the electrophoresis system at that time called the pH isolistrik. At pH there is a balance between these forms of amino acids as amphoteric ion, anion and cation (Anna Poedjiadi, 1994).
Carboxyl groups on the amino acid can be removed by decarboxylation process and produce an amine. Amino group in amino acids can react with nitric acid and release the nitrogen gas that can be measured by volume. Van Slyke using this reaction to determine the free amino group in amino acids, peptides and proteins. (Anna Poedjiadi, 1994)
Basically an acyl-peptide is an amino acid, because the-COOH and-NH 2 to form a peptide bond. Peptides derived from hydrolysis of proteins that are not perfect. If the resulting peptides will be generated further hydrolyzed amino acids. (Anna Poedjiadi, 1994).
Basically an acyl-peptide is an amino acid, because the-COOH and-NH 2 to form a peptide bond. Peptides derived from hydrolysis of proteins that are not perfect. If the resulting peptides will be generated further hydrolyzed amino acids. (Anna Poedjiadi, 1994).
Properties of peptides are determined by group-COOH,-NH2 and the group R. Properties of acids and bases on the peptides are determined by group-COOH and-NH 2, but in the long chainCOOH group and-NH2 located tip of the chain are no longer influential. A peptide also has a point isolistrik as in amino acids. Biuret color reaction is a reaction to peptides and proteins. (Anna Poedjiadi, 1994). The structure of proteins can be divided into four forms: primary, secondary, tertiary and quaternary. Linear arrangement of amino acids in proteins is the primary structure. The composition will determine the nature and form of the protein secondary and tertiary structure. When protein menandung many amino acids with hydrophobic groups, the solubility in water less than the proteins that contain lots of amino acids with hydrophilic groups. (Winarno, 1992).
Protein contained in food susceptible to changes, among others:
1. Can be denatured by heat treatment.
2. Can terkoagulasi or precipitated by acidification treatment.
3. Can decompose or breakdown by proteolytic enzymes.
4. Can react with reducing sugars, thus causing the brown color.
Protein denaturation can be interpreted a change or modification terhdap secondary str
ucture, tertiary and quaternary protein molecule without breaking the covalent bonds. Because it is a process of denaturation can be interpreted splitting of the hydrogen bonding, hydrophobic interactions, salt bonds and the opening of the protein molecules fold or pleat. (Winarno, 1992). Denaturation of proteins Protein denaturation can be interpreted a change or modification to the structure of the secondary, tertiary and quaternary protein molecule without breaking the bonds kovelen. Therefore, the denaturation can be interpreted a process of splitting of hydrogen bonding, hydrophobic interactions, salt and aterbukanya bonding pleat folds or protein molecules (Winarno, 1992).
Which the denatured protein will decrease its solubility. Inner molecular layer of hydrophobic ersifat will come out while the hydrophilic part will be folded into. Folding or pembakikkan will occur when the pH approached the protein and protein isoelektris will agglomerate and settle. Viscosity will increase as the molecules expand into asymmetric, optical rotation angle will also increase the protein solution (Winarno, 1992).
Denaturation of proteins involves disruption and damage that may occur in secondary and tertiary structures of proteins. Since denaturation reactions is not known to be strong enough to break the peptide bond, where the protein primary structure remains the same after the denaturation process. Denaturation occurs due to a disturbance in the secondary and tertiary structures of proteins. At the tertiary protein structure there are four types of interactions that form bonds to the side chain such as hydrogen bonding, salt bridges, disulfide bonds and hydrophobic non-polar interactions, which are likely to experience interference. Denaturation commonly encountered is the process of precipitation and coagulation proteins (Ophart, CE, 2003).
Denaturation due to heat:
Heat can be used to disrupt hydrogen bonding and hydrophobic non-polar interactions. This occurs because high temperatures can increase the kinetic energy and cause the building blocks of protein molecules move or vibrate so fast that disrupt the molecular bonds. Egg protein denaturation and terkoagulasi experienced during ripening. Some food is cooked to mendenaturasi proteins to facilitate the digestive enzymes contained in the digest of these proteins (Ophart, CE, 2003).
Heat can be used to disrupt hydrogen bonding and hydrophobic non-polar interactions. This occurs because high temperatures can increase the kinetic energy and cause the building blocks of protein molecules move or vibrate so fast that disrupt the molecular bonds. Egg protein denaturation and terkoagulasi experienced during ripening. Some food is cooked to mendenaturasi proteins to facilitate the digestive enzymes contained in the digest of these proteins (Ophart, CE, 2003).
Warming will make proteins denatured material so that the water binding capacity decreased. This happens because the thermal energy will lead to dissolution of non-covalent interactions that exist in the natural structure of the protein but did not decide the form covalent bond peptide bond. This process usually takes place in a narrow temperature range (Ophart, CE, 2003).
Alcohol can damage the hydrogen bonds:
Hydrogen bonding occurs between amide groups in the secondary structure of proteins. Hydrogen bonds between side chains occur in the tertiary structure of proteins with various combinations of its constituent amino acids (Ophart, CE, 2003)
Which the denatured protein will decrease its solubility. Layers of protein molecules in the hydrophobic part will come out, while the hydrophilic part will be folded into. Folding or reversal occurs when the pH approached the protein solution isoelektris, then the protein will coagulate and settle. Viscosity will increase as the molecule expands and becomes asymmetric, the optical rotation angle will also increase the protein solution. Protein denaturation can be caused by heat, pH, chemicals, mechanical and others. (Winarno, 1992)
Protein will experience precipitation when reacted with metal ions. Precipitation by positive ions (metal) is required on the ph solution of pi because negatively charged proteins, precipitation by negative ions is required under the ph of a solution of pi because the protein is positively charged. Positive ions that can precipitate the proteins are: Ag +, Ca + +, Zn + +, Hg + +, Fe + +, Cu + + and Pb + +, while the negative ions that can precipitate the proteins are; ion salicylate, triklorasetat, piktrat, tanat and sulfosalisilat. (Anna, P., 1994).
Protein will experience the greatest turbidity when the pH reaches ph isoelektris where the protein has a positive and negative charges are equal, at this moment marked denaturation of proteins has increased and the incidence of clot turbidity. (Anna, P., 1994). In general, levels of protein in the food determines the quality of food itself (SA & Suwedo H., 1987). Nutritional value of a food is determined not only by the levels of nutrients it contains, but also by whether or not nutrients are used by the body (Muchtadi, 1989). One parameter is the nutritional value of protein cernanya power which is defined as the effectiveness of protein absorption by the body (Del Valle, 1981). Based on the content of essential amino acids-Asan, food can be judged whether or not highly nutritious. High nutritional value of foodstuffs containing essential amino acids if complete and arrangement according to the needs of the body.
Easily digestible proteins that show a high number of amino acids can be absorbed by the body and vice versa. Several factors can affect the digestibility of protein in the body is the physical and chemical conditions. The harder the material, it will reduce the power cernanya in the body because of the complex bonds contained in the materials that are stronger. These bonds can form bonds between the molecules of the protein, binding protein-phytate, and sebaginya. While the chemical conditions of the existence of anti-nutritional compounds such as trypsin inhibitor and phytate (Muchtadi, 1989).
To determine the quality of protein in food ingredients can be carried out in vitro, the method of determination kulaitas khemis proteins based on protein breakdown by proteolytic enzymes such as pepsin, trypsin, khimotripsin, and aminopeptidase (Narasimha, 1978). The analysis provides an overview of the process of protein digestion in the stomach and intestines.
Enzymes are commonly used in the experiments is the enzyme pepsin which is a group of enzymes endopeptidase, which can hydrolyze peptide bonds at the center along the polypeptide chain and worked optimum at pH 2 and is stable at pH 2-5. This enzyme is produced in the form of pepsinogen which are not yet active in the resin hull. Pepsin is in an inactive state of perfect at neutral and alkaline conditions. This enzyme works by breaking down proteins into proteosa and peptone (Del Valle, 1981).
Enzymes are commonly used in the experiments is the enzyme pepsin which is a group of enzymes endopeptidase, which can hydrolyze peptide bonds at the center along the polypeptide chain and worked optimum at pH 2 and is stable at pH 2-5. This enzyme is produced in the form of pepsinogen which are not yet active in the resin hull. Pepsin is in an inactive state of perfect at neutral and alkaline conditions. This enzyme works by breaking down proteins into proteosa and peptone (Del Valle, 1981).
Analysis of proteins in vitro is divided into two methods. The first method is the pepsin digest residue index (PDR) using the enzyme pepsin as penghidrolisis protein samples. While the second method is the pepsin pancreatin digest index that uses two kinds of enzymes pepsin and pancreatin. In both methods are compared to the amount of nitrogen in the sample and the sample residue after hydrolysis by the enzyme.alibration is done by determining the amount of protein nitrogen amount contained by a substance. Material total N was measured by using micro-Kjeldahl method. The principle of this method is the oxidation of organic compounds by sulfuric acid to form CO2 and H2O as well as the release of ammonia nitrogen in the form of the protein determination based on the number N. In the determination of protein nitrogen should only be derived from protein are determined. However, this technique is difficult to do considering the content of N compounds other than proteins in the material are also shipped with this analysis. The number of compounds are usually very small N, including urea, nucleic acids, ammonia, nitrate, nitrite, amino acids, amides, purines, and pyrimidines. Therefore, the determination of total N was still being done to represent the amount of protein available. Protein levels determined in this manner commonly referred to as the protein content / crude protein (Sudarmadji, 1996). Kjeldahl protein analysis means basically divided into three stages namely destruction process, distillation and titration .
Determination of water content in foodstuffs can be done in various ways, as this depends on the nature of the material. In the experiment, analysis of water content is determined by the method of drying (Thermogravimetri). The principle is to evaporate the water present in the material by heating, then weigh the ingredients until a constant weight, which means all the water has evaporated. This method is relatively easy and inexpensive, but have various drawbacks. Among them are .
v Other materials besides water also evaporate and go away along with the steam. For example alcohol, acetic acid, aksim oil, etc..
v It may occur during the reaction that produces heating water or other volatile substances. Example: to decompose or caramelization of sugar, fat oxidation, etc..
v Materials that contain ingredients that bind water very strongly even though it was releasing water heated.
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