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Protein



CHAPTER I: INTRODUCTION
1.1 Background
Protein (the root word from the Greek protos, meaning "the ultimate") is a complex organic compounds of high molecular weight polymer of a monomer-monomer amino acids linked together by peptide bonds. Protein molecules containing carbon, hydrogen, oxygen, nitrogen and sometimes sulfur and phosphorus. Protein plays an important role in the structure and function of all living cells and viruses.
Most proteins are enzymes or enzyme subunits. Other types of proteins play a role in structural or mechanical functions, such as proteins that form the stems and joints Cytoskeleton. Protein involved in the immune system (immune) as an antibody, the control system in the form of the hormone, as a storage component (the seeds) and also in the transport of nutrients. As one source of nutrition, proteins serve as a source of amino acids for organisms that are not able to form these amino acids (heterotrof).

Protein is one of the giant biomolecules, in addition to polysaccharides, lipids, and polinukleotida, which is the main constituent of living things. In addition, the protein molecule is one of the most widely studied in biochemistry. Proteins discovered by Jöns Jakob Berzelius in 1838.
Biosynthesis of natural proteins with genetic expression. Which carried the genetic code of DNA is transcribed into RNA, which acts as a template for translation is done ribosomes. Until this stage, the protein is still "raw", only composed of amino acids proteinogenik. POSTTRANSLATION http://www.blogger.com/moderate-comment.g?blogID=6973991885859588855Melalui mechanism, formed a protein that has full biological function.

CHAPTER II DISCUSSION
2.1 Composition of Proteins Protein consisting of carbon, hydrogen, oxygen, nitrogen, and, in some cases, sulfur. Protein is the only nitrogen-containing nutrients, a fact which makes it both essential and potentially toxic. Amino acids are the building blocks of larger structures of protein molecules. Some of these amino acids can be synthesized from other amino acids (called nonessential amino acids), while some must be obtained from the food we eat (referred to as essential amino acids). Once connected in the chain of proteins, individual amino acids called the residue, and a series of related carbon, nitrogen, and oxygen atoms known as the main chain or protein backbone.

2.2 Protein Structure Protein structure can be seen as a hierarchy, that is, the primary structure (one level), secondary (level two), the tertiary (level three), and kuartener (level four). The primary structure of proteins is a constituent amino acid sequence of a protein linked via a peptide bond (amide). Meanwhile, the secondary structure of proteins is a local three-dimensional structure of the various amino acid sequences of proteins stabilized by hydrogen bonds. Various forms of such secondary structure is as follows: • alpha helix (α-helix, "torsion-alpha"), a wrench chain amino acids shaped like a spiral; • beta-sheet (β-sheet, "plate-beta"), a broad sheet composed of a number of amino acid chains that are held together by hydrogen bonds or bond thiol (SH); • beta-turn, (β-turn, "curve-beta"); and • gamma-turn, (γ-turn, "gamma-curve").
A combination of a variety of secondary structure will produce three-dimensional structure of the so-called tertiary structure. Tertiary structure is usually a clot. Some protein molecules can physically interact without forming covalent bonds are stable Oligomer (eg dimer, trimer, or kuartomer) and kuartener structure. Examples of the famous structure is kuartener enzyme Rubisco and insulin.
Protein primary structure can be determined by several methods: (1) hydrolysis of proteins with strong acids (eg, 6N HCl) and then the amino acid composition determined by amino acid analyzer instruments, (2) sequence analysis of end-N by using Edman degradation, ( 3) a combination of digestion with trypsin and mass spectrometry, and (4) the determination of molecular mass by mass spectrometry.
Secondary structure can be determined by using circular dichroism spectroscopy (CD) and Fourier Transform Infra Red (FTIR). CD spectrum of the torsion-alpha showed two negative absorbans at 208 and 220 nm, and plate-beta showed a negative peak around 210-216 nm. Estimation of the composition of protein secondary structure can be calculated from the CD spectrum. In the FTIR spectrum, the amide-I bands of different torsion-alpha compared with the amide bands of plate-I-beta. Thus, the composition of protein secondary structure can also be estimated from the infrared spectrum.
Other protein structures are also known domain. This structure consists of amino acids 40-350. Simple proteins generally have only one domain. In the more complex proteins, there are multiple domains involved in it. Polypeptide chain relationships play a role in it will create a new function different from their constituent parts. If the domain structure of this complex structure apart, the biological function of each constituent domain components are not lost. This is what distinguishes domain structure with kuartener structure. Kuartener structure, the complex structure of separate, it does not fungsional.Kekurangan proteins Protein
Protein itself has many functions in our body. Basically support the existence of protein per cell body, the immune process. Every adult should consume at least 1 g protein kg body weight pro. The need for protein increases in women who are pregnant and atlet.atlet.
Protein structures can be determined by X-ray crystallography or NMR spectroscopy. However, both methods are very time consuming and relatively expensive. Meanwhile, protein sequencing methods are relatively easy to express a protein amino acid sequence. Protein structure prediction to predict three-dimensional structure of proteins based on amino acid sequence. In other words, the prediction of secondary structure and predicted tertiary structure based on the primary structure of proteins.
Protein structure prediction methods available today can be categorized into two groups, namely the comparative protein modeling methods and modeling methods de novo. Comparative protein modeling (comparative protein modeling) to predict the structure of a protein based on other protein structures that have been identified. One application of this method is the homology modeling, the prediction of protein tertiary structure based on the similarity of primary structure of proteins. Homology modeling based on the theory that the two homologous proteins have a structure very similar to each other.
In this method, the structure of a protein called with the target protein, determined by the structure of other proteins or protein templet, which have been identified and has sequence similarity with the target protein. In addition, another application of comparative modeling of protein threading is based on the similarity of the structure without primary sequence similarity. Threading protein background is that protein structure is more conserved than protein sequence during evolution; areas that are important to maintain the structure of protein function. In this approach, the most compatible structure for an amino acid sequence selected from any type of three-dimensional structure of proteins that exist. The methods belonging to the protein threading trying to determine the level of compatibility.
Protein structure can be determined from the primary sequences without comparing with other protein structures based approach to de novo or ab initio. There are many possibilities in this approach, for example, by imitating the process of folding (folding) of proteins from primary sequence into tersiernya structure (eg by molecular dynamics simulation), or with the global optimization of energy function of proteins. These procedures tend to require intense computational process that is currently only used in determining the structure of small proteins.

Based on molecular structure, proteins can be divided into 3 main groups, namely:
1. Proteins form fibers (fibrous) Protein fibers form consists of several peptide chains intertwined spiral from one another that resembles a rigid rod. Characteristics of protein fibers is the low solubility, high mechanical mempunyaikekuatan and are resistant to digestive enzymes. This protein is found in the elements of structure (collagen, elastin, keratin, and myosin).

2. Globular proteins Spherical globular protein, found in the body tissue fluid. These proteins soluble in salt solutions and dilute acids, easily changed under the influence of temperature. Included in globular proteins are (albumin, globulin, histones, and Protamin).

3. Protein Conjugation Protein conjugate is a simple protein that bound to the material non-acidic amino acids. Included in globular proteins are (nucleoprotein, lipoprotein, Fosfoprotein and Metaloprotein)


2.3 Protein Function Protein in the food will be involved in the formation of protein networks, and variety of specific metabolic functions. • Growth (for children) and maintenance (for adults) Iubah proteins into amino acids needed to build and maintain body tissue. • Establishment of essential bonds of the body • Set the water balance • Maintaining the neutrality of the body • Formation of antibodies
Proteins involved in immune system function. • Transporting nutrients • Source of energy
Hormones are chemical introduction together and issued by the tissue (glandular) endocrine and carry blood to the tissue or organs, binding to a cell that is sensitive to stimulation of protein. Enzymes are protein molecules (shown suffix ase) serves as a catalyst for change timngkat reaction in the body. Enzymes in classified according to type of reaction mengkatalisasinya example: Hidrolases split-mixed. -Isomerases move atoms in a molecule. -Ligases (synthases) joined with its mixture. Electron-transfer Oxidereductases. Transverases move-functional groups

2.4 Lack of Protein Protein itself has many functions in our body. Basically support the existence of protein per cell body, the immune process. Every adult should consume at least 1 g protein kg body weight pro. The need for protein increases in women who are pregnant and atlet.atlet. Protein deficiency can be fatal: a. Hair loss (hair consists of 97-100% of the protein-keratin) b. The worst is called the [[kwashiorkor], protein deficiency disease. Usually in small children who are suffering, can be seen from the name starvation, caused by the filtration of water in the blood vessels leading to other odem.Simptom be recognized are: • hipotonus • growth disorders • fatty liver
c. Lack of continuous berkibat cause marasmus and death.

2.5 Source of Protein • Meat • Fish • Eggs • Milk, and similar products Quark • Plant berbji • Interest legumes • Potatoes Biochemists study from the USA Lafayete Thomas Osborne Mendel, Professor for biochemistry at Yale, 1914, mengujicobakan proteinkonsumsi from meat and plants to the rabbits. One group of rabbits were given a diet of animal protein, while the other group was given vegetable protein. From his experiments found that the rabbit is getting faster animal protein increases the weight of the rabbits that received vegetable protein. Then the next study, by McCay of the University of Berkeley showed that the rabbits are getting protein, vegetable, healthier and live twice as long.
Crude Protein 2.6 and True Protein In general, there are 3 kinds of major organic components in each formulation diet / ruminant animal feed. The third component is the Carbohydrates (eg: Celulosa and starches), lipids (fats and oils), and protein. Protein can be divided into 2 main classes, namely Crude Protein (Crude Protein) and protein Sejati (True Protein). True protein composed of amino acids (Amino Acids) long-chain and each protein was to be different because it is composed of 20 amino acids of the sequence was unique (Figure 1)

Figure 1: Schematic diagram of the True Protein. Each protein has unique characteristics because of the shape and sequence of its amino acids. Most proteins consist of several hundred to several thousand amino acid chain (Dairy Research & Technology Center, University of Alabama)
In the laboratory feed, a protein isolated from carbohydrates and lipids that contain nitrogen (N) on these proteins - in general, food proteins typically contain 16% N. This separation allows the researchers to estimate the protein content of a feed material by measuring the N content was then multiplied by the numbers 6:25 (inverse ratio of 16%). However, not all N in the feed material is a protein, N protein is not called non-protein nitrogen (NPN). NPN can be found in the feed components such as urea, ammonium salts and a single amino acid. Therefore, the value obtained from the total product of N with 6:25 commonly called protein Rough (Crude protein; CP)
Protein decomposition A few percent of crude protein contained in the feed material in the consumption of cow (also called protein intake) in the described by microbes in the cow rumen. In the NRC system (National Research Centers - U.S. agency that issued the standards and tables nutritional needs of cattle) in this case named degradable intake protein (DIP).
At different proteins True, its decomposition rate is not the same. Some types can be described in full in just 30 minutes after reaching the rumen, whereas other types may take several days before it can be explained. Compare with NPN in the protein components that can be described Rough immediately when entering the rumen.
Because the protein in the feed material that can decompose quickly properties can most soluble (soluble), measurement of soluble protein (soluble protein) in the laboratory scale can be considered to show the proportion of crude protein that breaks down, in which proteins are the fastest substance described in in the rumen.
Even so, it is important to keep in mind that some sources of soluble proteins (eg, blood meal) relative to decompose more slowly.
In figure 2 below, the output of pengurain DIP (mainly ammonia and amino acids) used for microbial cells to replace other microbial cells that were swept along with other feed materials from the rumen, and in particular, to the small bowel (small intestine).

At the time of the protein is described in the rumen, the rest shot feed (feed residue) are also flowing out of the rumen to the omasum, abomasum for the next arrived in the small intestine. Therefore, when the speed of protein breakdown (in the rumen) defeated quickly by the flow out of feed ingredients, the protein material to escape from rumen microbial decomposition. This protein is called off (escape or bypass protein). NRC calls for UIP (undegradable intake protein). The release will be 2.7 Linear Increasing the feed intake At the feed material is a protein substance decomposes slowly, slowing down the journey level material (passage rate) through the rumen, the microbes have the opportunity to describe these materials and make the value smaller UIP (fig 3). That needs to be remembered, passsage rate will increase when food intake increased. For that reason, UIP value will be lower when the protein source of feed ingredients such as flour off the corn cereal (corn gluten meal) is given to cows that consume the dry period dry ingredients (dry matter) as much as 2% body weight, compared to lactation cows that consume twice more (4% body weight).
Because the tempo and rhythm of rumen storage will affect the ability of dust from the rumen, the value of the release of a feed material is not constant, but will change as the change of feed intake level.
Figure 3: The decomposition is highly dependent on two things, the nature and duration of feed materials such material in the rumen. When the intake of feed (feed intake) and the speed of travel of feed from rumen increased, while the storage material in the rumen and less decomposition by microbes. (Dairy Research & Technology Center, University of Alabama).
Protein 2.8 Ketercernaan Approximately 80-85% of microbial protein and UIP pengurai that flows out of the rumen is digested in the small intestine. However, UIP from different types of feed materials mostly have a low digestive power. Especially on green materials and waste feed agricultural production has experienced a high heating process contains proteins that have been damaged by heat (heat-damaged proteins) that in the laboratory feed called Adin (acid detergent insoluble nitrogen). Although in some feed materials through moderate warming could actually increase the protein quality off (bypass value), excessive heat (excessive heat) can make some of UIP can be digested, so no use for livestock.
2.9 Amino Acid Balance The final result of the breakdown of proteins in the small intestine is an amino acid. This amino acid is then absorbed by the bloodstream and used by cattle for growth, tissue maintenance and milk production. From about 20 kinds of amino acids present in protein sources of feed material, 10 species can be produced by the cow. The rest that can not be in production by the cow is called essential amino acids (EAA; essential amino acids). To ensure the consumption of a balanced amino acid, EAA should be located in the small intestine in the form of microbial protein produced or feed UIP. Ideally, the relative proportions of each of the EAA absorbed by cattle could provide exactly the needs of livestock, this is due to the absence of one type of amino acids may limit the use of other types. This makes inefficient feeding. Imagine this by example when we did the mixing of feed materials in seven ration TMR (total mixed ration). Allotment materials require constant proportion of each material. If you lack one of the ingredients, the amount of the 6 other ingredients can be mixed to create a fixed ratio proportionally limited, this results in the quantity that can be made TMR less.
Proteins produced by microbes contain a mixture of EAA is still far from ideal when compared to relative to the needs of a cow that had high production. The main target of the selection of protein ingredients and elements to produce off is UIP (EAA-containing alloys) are able to meet the shortage of amino acids produced by microbial protein maker.
Most research on current nutrition in focus for seeking and determining needs in a more appropriate EAA and EAA predict which ones could be the limit.
Absorption and transport 2:10
After the digestive process is active in the small intestine in the form of the protein amino acids will be absorbed through the epithelial cells of smooth walls. All the amino acids that dissolve in water can easily diffuse passively through the cell membrane. Absorption of amino acids involves several aspects: 1. Active transport Here amino acids will be absorbed naturally by diffusion activities. 2. Kovaktor vitamin B6 Vitamin B6 is needed for the transport of amino acids into the network. 3. Competence / competition In the absorption when the mixture of amino acids that have a dominant number will inhibit other amino acids. 4. absorption of intact proteins polypeptide fragments rather large, even in the form of protein that can not be absorbed, digested directly. Protein Metabolism 2:11 The main metabolic pathways of amino acids The main metabolic pathways of amino acids consisting of: 1. Production of amino acids from the demolition of protein body digest dietary protein and amino acid synthesis in the liver. 2. Capture nitrogen from amino acids. 3. Catabolism of amino acids into energy through acid cycle and urea cycle as a processing byproduct of amino acid solution. 4. Synthesis of protein from amino acids.
2:12 protein quality evaluation method Five methods described below are the most frequently used to assess the quality of the protein. 1. Protein digestibility corrected amino acid already Score * (PDCAAS): The amino acid score by digestibility additional components. PDCAAS received today is measuring the protein quality due to determinations made close to compare it with animals. Some nutrition experts feel this method should be studied further improvements and additional changes can be seen in the future. 2. Amino acid score (AAS) Chemical technique is considered quick, consistent, and inexpensive. Tool indispensable amino acids present in proteins and compared with the reference value of proteins. That protein is based on the most limiting value of amino acids indispensable. Value greater than 1.0 for both AAS and PCDAAS be shown that the protein contains essential amino acids in excess of human needs. Therefore, in the year 1990 at the FAO / WHO meeting it was decided that the protein has a higher value than 1.0 will be rounded down 1.0. This point is in the debate as experts feel that the rounding down of high quality protein fails to reflect the ability of proteins to complement the nutritional value of lower-quality protein. 3. Protein Efficiency Ratio (PER) The size of the protein's ability to support the growth of weanling rats. This represents the ratio of weight to get the amount of protein consumed. This method has two main concerns. First is the attention that can not be applied to the growth of infants and children as the amino acid requirements for growth in babies less than those for rats. Second, PER growth steps but not the maintenance, so you may use the limitations in determining protein requirements in adults. 4. Biological Value (BV) Measure of the amount of nitrogen fixed compared with the amount of nitrogen absorbed. The BV and NPU method reflects both the availability and digestibility, and they provide an accurate assessment of maintenance needs. 5.Nitrogen Protein Utilization (NPU): the ratio of nitrogen used for tissue formation compared with the amount of nitrogen digested.

CHAPTER III CLOSING

3.1 CONCLUSIONS 1. Proteins are complex organic compounds of high molecular weight polymer of a monomer-amino acid monomers linked to each other by peptide bonds. 2. Protein consisting of carbon, hydrogen, oxygen, nitrogen, and, in some cases, sulfur. 3. Protein structure can be seen as a hierarchy, that is, the primary structure (one level), secondary (level two), the tertiary (level three), and kuartener (level four) 4. Based on molecular structure, proteins can be divided into 3 main groups, namely: a. Proteins form fibers (fibrous) b. Globular proteins c. Protein Conjugation 5. Protein Function: • Growth (for children) and maintenance (for adults) • Establishment of essential bonds of the body • Set the water balance • Maintaining the neutrality of the body • Formation of antibodies • Transporting nutrients • Source of energy 6. Protein can be divided into 2 main classes, namely Crude Protein (Crude Protein) and protein Sejati (True Protein)

REFERENCES

Badley R.A., D. Atkinson, H. Hauser, D. Oldani, J.P. Green, and J.M. Stubbs, 1975. The structure, physical, and chemical properties of the soybean protein glycinin. Biochem. Biophys. Acta. 412, 214.
A.W. Burks, H.L. Butler, J.R. Brooks, J. Hardin, and C. Connaughton, 1988.Identification and comparison of differences in antigens in two Commercially available soybean protein isolates. J. Food Sci. 53, 1456.
C.E. Danielson, 1949. Seed globulins of the Gramineae and Leguminosae. Biochem. J. 44, 387.
Genovese M.I. and F.M. Lajolo, 1993. Composition and structural characteristics of isolated soy proteins from broken and damaged seeds. J. Food Sci. 58, 148.
http / /: id.wikipedia.org / wiki / Protein

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