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Архитектура Аудит Военная наука Иностранные языки Медицина Металлургия Метрология Образование Политология Производство Психология Стандартизация Технологии |
Classification of Amino AcidsСтр 1 из 4Следующая ⇒
Plan Introduction · Subject of Biochemistry M ain part · Amino Acids · Essential Amino Acids · Protein structure molecule C onclusion L iterature used Introduction Subject of Biochemistry Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and relating to living organisms. Biochemical processes give rise to the complexity of life. A sub-discipline of both biology and chemistry, biochemistry can be divided in three fields; molecular genetics, protein science and metabolism. Over the last decades of the 20th century, biochemistry has through these three disciplines become successful at explaining living processes. Almost all areas of the life sciences are being uncovered and developed by biochemical methodology and research. Biochemistry focuses on understanding how biological molecules give rise to the processes that occur within living cells and between cells, which in turn relates greatly to the study and understanding of tissues, organs, and organism structure and function. Biochemistry is closely related to molecular biology, the study of the molecular mechanisms by which genetic information encoded in DNA is able to result in the processes of life. Much of biochemistry deals with the structures, functions and interactions of biological macromolecules, such as proteins, nucleic acids, carbohydrates and lipids, which provide the structure of cells and perform many of the functions associated with life. The chemistry of the cell also depends on the reactions of smaller molecules and ions. These can be inorganic, for example water and metal ions, or organic, for example the amino acids, which are used to synthesize proteins. The mechanisms by which cells harness energy from their environment via chemical reactions are known as metabolism. The findings of biochemistry are applied primarily in medicine, nutrition, and agriculture. In medicine, biochemists investigate the causes and cures of diseases. In nutrition, they study how to maintain health wellness and study the effects of nutritional deficiencies. In agriculture, biochemists investigate soil and fertilizers, and try to discover ways to improve crop cultivation, crop storage and pest control.
M ain part Amino Acids All metabolic activities of living bodies are regulated by Biomolecules. There are mainly four types of Biomolecules which take part in almost all the metabolic activities of living cells. These Biomolecules are carbohydrates, lipids, proteins and nucleic acid. These are polymeric forms of some monomer units. For example; proteins are composed of amino acids that are bonded to each other through peptide linkage. Amino acids are organic molecules with two functional groups which are bonded to the same carbon atom of the molecule. One is an amino group (-NH2) and another is carboxylic group (-COOH). The carbon atom, at which both of the functional groups are bonded, is known as the alpha carbon atom and such amino acids are known as alpha amino acids. Only alpha amino acids involve in the polymerisation to form protein molecule. Beta and gamma amino acids cannot form protein molecules. The amino group of one amino acid is involved in a condensation reaction with carboxyl group of another amino acid to form –CO-NH- linkage. This linkage is called as a peptide bond. Do you know both the functional groups of an amino acid molecule have different nature? One is acidic and another is alkaline in nature. Then what will be the nature of an amino acid molecule? Let’s discuss the properties of different amino acid molecules Amino Acid Defenition Amino acids are generally referred as α α amino acids. The general formula for amino acid is H2NCHRCOOH. Here 'R' is the functional group of the amino acids.
Ball and stick model The amino group is attached to the carbon atom immediately next to the carboxylate group that is α α carbon, so, it is called α α amino acids. Other amino acids also exist called beta and gamma amino acids, in which the amino group is attached to the carbon which is next to α α carbon called α α amino acid and the next is called α α amino acid.
Non Polar Amino Acids
Essential Amino Acids An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized de novo (from scratch) by the organism, and thus must be supplied in its diet. The nine amino acids humans cannot synthesize are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine. There are 9 " essential" amino acids and they are called " essential" because our bodies can't produce them, so it's essential that we include them in our daily diet. The nine essential amino acids are histidine, valine, isoleucine, leucine, phenylalanine, threonine, tryptophan, methionine, and lysine. Why are amino acids important? Amino acids are the building blocks of protein, which is a very important element for nearly all physiological functions. Most skeletal tissues, cells, organs, and muscles are made of amino acids. They help make the proteins that allow our bodies to grow, repair tissue, break down food, and perform many other essential biological processes. Branched-chain amino acids (BCAA) have a branched molecular structure. There are three of them: leucine, isoleucine, and valine. Like other essential amino acids, they are building blocks of proteins and muscles. They also help regulate blood sugar levels. BCAAs also help reduce fatigue during exercise. The 9 Essential Amino Acids
The 9 Essential Amino Acids Some sources list eight essential amino acids and others list nine. This is because histidine, which used to be considered essential only for infants was later reclassified as an essential amino acid when it was found to be indispensable for humans Other lists include histidine as well as arginine, which is only essential (must be added to the diet) for premature infants, who can't make it on their own. The 22 Amino Acids
Histidine Histidine is unique because it is both an essential and nonessential amino acid. The body needs histidine to develop and maintain healthy tissues, especially myelin sheath that coats nervous cells to ensure the transmission of messages from your brain to organs throughout your body. Too much histidine is associated with physiological disorders like anxiety and schizophrenia. Not enough can to lead to rheumatoid arthritis and deafness from nerve damage. Adults can typically produce enough histidine from other amino acids in the liver to support the body’s daily needs. But children must get histidine from food. This is especially true during infancy when adequate histidine levels are essential for proper growth and development. Foods that are high in protein generally contain high histidine levels as well. These foods include:, meat, poultry, and fish, dairy, rice, wheat, and rye, seafood, beans, eggs, buckwheat, corn, cauliflower, mushrooms, potatoes, bamboo shoots, bananas, cantaloupe, and citrus fruits Valine Valine, apart from being an essential amino acid, is one of the three branched-chain amino acids. The other two are leucine and isoleucine. Also together with leucine and isoleucine, valine belongs to the group of proteinogenic amino acids, which are the building blocks of proteins produced by cells that are recorded in the genetic code of each living thing. Valine is an important source of nitrogen, an important component in alanine and glutamine synthesis in the muscles. Foods rich in valine include:, cottage cheese, fish and poultry, sesame seeds lentils, tofu, egg whites, peanuts, beef and lamb, gelatin Isoleucine Isoleucine is another branched-chain amino acid. It cannot be produced in the body and must be obtained from the food we eat. Isoleucine is essential for proper blood-clotting and muscle repair. While isoleucine deficiency is uncommon, symptoms include dizziness, fatigue, headaches, confusion, irritability, and depression. Isoleucine has several key roles in healthy body functions. · It regulates blood sugar and boosts the body's energy levels. · It plays a key role in the transport of oxygen from the lungs to the various parts of the body and the production of hemoglobin, which contains iron. · It is important for the efficient metabolism of glucose, as manifested by the increase in the absorption of sugar. When given orally, isoleucine reduces the level of sugar in the blood by 20 percent and increases sugar absorption in the muscles by 71 percent without necessarily increasing the level of insulin in the blood. Good sources of isoleucine are: eggs, chicken, fish, cheese, soybeans, seaweed, turkey Protein structure molecule Protein structure is the three-dimensional arrangement of atoms in an amino acid-chain molecule. Proteins are polymers – specifically polypeptides – formed from sequences of amino acids, the monomers of the polymer. A single amino acid monomer may also be called a residue indicating a repeating unit of a polymer. Proteins form by amino acids undergoing condensation reactions, in which the amino acids lose one water molecule per reaction in order to attach to one another with a peptide bond. By convention, a chain under 30 amino acids is often identified as a peptide, rather than a protein. To be able to perform their biological function, proteins fold into one or more specific spatial conformations driven by a number of non-covalent interactions such as hydrogen bonding, ionic interactions, Van der Waals forces, and hydrophobic packing. To understand the functions of proteins at a molecular level, it is often necessary to determine their three-dimensional structure. This is the topic of the scientific field of structural biology, which employs techniques such as X-ray crystallography, NMR spectroscopy, and dual polarisation interferometry to determine the structure of proteins. Protein structures range in size from tens to several thousand amino acids. By physical size, proteins are classified as nanoparticles, between 1–100 nm. Very large aggregates can be formed from protein subunits. For example, many thousands of actin molecules assemble into a microfilament. A protein generally undergo reversible structural changes in performing its biological function. The alternative structures of the same protein are referred to as different conformational isomers, or simply, conformations, and transitions between them are called conformational changes. Primary structure The primary structure of a protein refers to the sequence of amino acids in the polypeptide chain. The primary structure is held together by peptide bonds that are made during the process of protein biosynthesis. The two ends of the polypeptide chain are referred to as the carboxyl terminus (C-terminus) and the amino terminus (N-terminus) based on the nature of the free group on each extremity. Counting of residues always starts at the N-terminal end (NH2-group), which is the end where the amino group is not involved in a peptide bond. The primary structure of a protein is determined by the gene corresponding to the protein. A specific sequence of nucleotides in DNA is transcribed into mRNA, which is read by the ribosome in a process called translation. The sequence of amino acids in insulin was discovered by Frederick Sanger, establishing that proteins have defining amino acid sequences. The sequence of a protein is unique to that protein, and defines the structure and function of the protein. The sequence of a protein can be determined by methods such as Edman degradation or tandem mass spectrometry. Often, however, it is read directly from the sequence of the gene using the genetic code. It is strictly recommended to use the words " amino acid residues" when discussing proteins because when a peptide bond is formed, a water molecule is lost, and therefore proteins are made up of amino acid residues. Post-translational modification such as phosphorylations and glycosyla-tions are usually also considered a part of the primary structure, and cannot be read from the gene. For example, insulin is composed of 51 amino acids in 2 chains. One chain has 31 amino acids, and the other has 20 amino acids. Secondary structure Secondary structure refers to highly regular local sub-structures on the actual polypeptide backbone chain. Two main types of secondary structure, the α -helixand the β -strand or β -sheets, were suggested in 1951 by Linus Pauling et al. These secondary structures are defined by patterns of hydrogen bonds between the main-chain peptide groups. They have a regular geometry, being constrained to specific values of the dihedral angles ψ and φ on the Ramachandran plot. Both the α -helix and the β -sheet represent a way of saturating all the hydrogen bond donors and acceptors in the peptide backbone. Some parts of the protein are ordered but do not form any regular structures. They should not be confused with random coil, an unfolded polypeptide chain lacking any fixed three-dimensional structure. Several sequential secondary structures may form a " supersecondary unit". Tertiary structure Tertiary structure refers to the three-dimensional structure of monomeric and multimeric protein molecules. The α -helixes and β -pleated-sheets are folded into a compact globular structure. The folding is driven by the non-specific hydrophobic interactions, the burial of hydrophobic residues from water, but the structure is stable only when the parts of a protein domain are locked into place by specific tertiary interactions, such as salt bridges, hydrogen bonds, and the tight packing of side chains and disulfide bonds. The disulfide bonds are extremely rare in cytosolic proteins, since the cytosol (intracellular fluid) is generally a reducingenvironment. Quaternary structure Quaternary structure is the three-dimensional structure consisting of the aggregation of two or more individual polypeptide chains (subunits) that operate as a single functional unit (multimer). The resulting multimer is stabilized by the same non-covalent interactions and disulfide bonds as in tertiary structure. There are many possible quaternary structure organisations. Complexes of two or more polypeptides (i.e. multiple subunits) are called multimers. Specifically it would be called a dimer if it contains two subunits, a trimer if it contains three subunits, a tetramer if it contains four subunits, and a pentamer if it contains five subunits. The subunits are frequently related to one another by symmetry operations, such as a 2-fold axis in a dimer. Multimers made up of identical subunits are referred to with a prefix of " homo-" (e.g. a homotetramer) and those made up of different subunits are referred to with a prefix of " hetero-", for example, a heterotetramer, such as the two alpha and two beta chains of hemoglobin. C onclusion Biochemistry, study of the chemical substances and processes that occur in plants, animals, and microorganisms and of the changes they undergo during development and life. It deals with the chemistry of life, and as such it draws on the techniques of analytical, organic, and physical chemistry, as well as those of physiologists concerned with the molecular basis of vital processes. All chemical changes within the organism-either the degradation of substances, generally to gain necessary energy, or the buildup of complex molecules necessary for life processes-are collectively termed metabolism. These chemical changes depend on the action of organic catalysts known as enzymes, and enzymes, in turn, depend for their existence on the genetic apparatus of the cell. It is not surprising, therefore, that biochemistry enters into the investigation of chemical changes in disease, drug action, and other aspects of medicine, as well as in nutrition, genetics, and agriculture. The term biochemistry is synonymous with two somewhat older terms: physiological chemistry and biological chemistry. Those aspects of biochemistry that deal with the chemistry and function of very large molecules (e.g., proteins and nucleic acids) are often grouped under the term molecular biology. Biochemistry is a young science, having been known under that term only since about 1900. Its origins, however, can be traced much further back; its early history is part of the early history of both physiology and chemistry. L iterature used · Peet, Alisa (2012). Marks, Allan; Lieberman Michael A., eds. Marks' Basic Medical Biochemistry (Lieberman, Marks's Basic Medical Biochemistry) (4th ed.). ISBN 978-1-60831-572-7. · Rayner-Canham, Marelene F.; Rayner-Canham, Marelene; Rayner-Canham, Geoffrey (2005). Women in Chemistry: Their Changing Roles from Alchemical Times to the Mid-Twentieth Century. Chemical Heritage Foundation. ISBN 978-0-941901-27-7. · Rojas-Ruiz, Fernando A.; Vargas-Mé ndez, Leonor Y.; Kouznetsov, Vladimir V. (2011). " Challenges and Perspectives of Chemical Biology, a Successful Multidisciplinary Field of Natural Sciences". Molecules. 16 (3): 2672–2687. doi: 10.3390/molecules16032672. PMC 6259834. PMID 21441869. · Saenger, Wolfram (1984). Principles of Nucleic Acid Structure. New York: Springer-Verlag. ISBN 978-0-387-90762-8. · Slabaugh, Michael R.; Seager, Spencer L. (2013). Organic and Biochemistry for Today (6th ed.). Pacific Grove: Brooks Cole. ISBN 978-1-133-60514-0.
Plan Introduction · Subject of Biochemistry M ain part · Amino Acids · Essential Amino Acids · Protein structure molecule C onclusion L iterature used Introduction Subject of Biochemistry Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and relating to living organisms. Biochemical processes give rise to the complexity of life. A sub-discipline of both biology and chemistry, biochemistry can be divided in three fields; molecular genetics, protein science and metabolism. Over the last decades of the 20th century, biochemistry has through these three disciplines become successful at explaining living processes. Almost all areas of the life sciences are being uncovered and developed by biochemical methodology and research. Biochemistry focuses on understanding how biological molecules give rise to the processes that occur within living cells and between cells, which in turn relates greatly to the study and understanding of tissues, organs, and organism structure and function. Biochemistry is closely related to molecular biology, the study of the molecular mechanisms by which genetic information encoded in DNA is able to result in the processes of life. Much of biochemistry deals with the structures, functions and interactions of biological macromolecules, such as proteins, nucleic acids, carbohydrates and lipids, which provide the structure of cells and perform many of the functions associated with life. The chemistry of the cell also depends on the reactions of smaller molecules and ions. These can be inorganic, for example water and metal ions, or organic, for example the amino acids, which are used to synthesize proteins. The mechanisms by which cells harness energy from their environment via chemical reactions are known as metabolism. The findings of biochemistry are applied primarily in medicine, nutrition, and agriculture. In medicine, biochemists investigate the causes and cures of diseases. In nutrition, they study how to maintain health wellness and study the effects of nutritional deficiencies. In agriculture, biochemists investigate soil and fertilizers, and try to discover ways to improve crop cultivation, crop storage and pest control.
M ain part Amino Acids All metabolic activities of living bodies are regulated by Biomolecules. There are mainly four types of Biomolecules which take part in almost all the metabolic activities of living cells. These Biomolecules are carbohydrates, lipids, proteins and nucleic acid. These are polymeric forms of some monomer units. For example; proteins are composed of amino acids that are bonded to each other through peptide linkage. Amino acids are organic molecules with two functional groups which are bonded to the same carbon atom of the molecule. One is an amino group (-NH2) and another is carboxylic group (-COOH). The carbon atom, at which both of the functional groups are bonded, is known as the alpha carbon atom and such amino acids are known as alpha amino acids. Only alpha amino acids involve in the polymerisation to form protein molecule. Beta and gamma amino acids cannot form protein molecules. The amino group of one amino acid is involved in a condensation reaction with carboxyl group of another amino acid to form –CO-NH- linkage. This linkage is called as a peptide bond. Do you know both the functional groups of an amino acid molecule have different nature? One is acidic and another is alkaline in nature. Then what will be the nature of an amino acid molecule? Let’s discuss the properties of different amino acid molecules Amino Acid Defenition Amino acids are generally referred as α α amino acids. The general formula for amino acid is H2NCHRCOOH. Here 'R' is the functional group of the amino acids.
Ball and stick model The amino group is attached to the carbon atom immediately next to the carboxylate group that is α α carbon, so, it is called α α amino acids. Other amino acids also exist called beta and gamma amino acids, in which the amino group is attached to the carbon which is next to α α carbon called α α amino acid and the next is called α α amino acid.
Classification of Amino Acids
1. Non-polar amino acids 2. Polar amino acids with no charge 3. Polar amino acids with positive charge 4. Polar amino acids with negative charge |
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