Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Western blot wikipedia , lookup
Nuclear magnetic resonance spectroscopy of proteins wikipedia , lookup
Protein folding wikipedia , lookup
Protein mass spectrometry wikipedia , lookup
Homology modeling wikipedia , lookup
List of types of proteins wikipedia , lookup
Circular dichroism wikipedia , lookup
Intrinsically disordered proteins wikipedia , lookup
GOVERNMENT ENGINEERING COLLEGE, BHARUCH Organic Chemistry and Unit Processes (2130501) Topic Name : Amino Acids & Protein Chemistry Guided by: Dr. Rita Agarwal 1 Prepared by: Parmar Bhagyashree Patel Apexa Mori Divyang Parmar Ajay Rathwa Siddharth 150143105007 150143105008 150143105005 150143105006 150143105011 Amino Acids Amino acids have both a carboxyl group -COOH an amino group -NH2 in the same molecule.. 3 Amino Acid Structure The general formula of an amino acid is shown here The group designated by R is usually a carbon chain but other structures are also possible 4 Amino Acid Structure Amino acids may be characterized as a, b , or g amino acids depending on the location of the amino group in the carbon chain. a are on the carbon adjacent to the carboxyl group. b are on the 2nd carbon g on the 3rd carbon from the carboxyl group 5 Amino Acids are Amphoteric Amino acids are amphoteric. They are capable of behaving as both an acid and a base, since they have both a proton donor group and a proton acceptor group. In neutral aqueous solutions the proton typically migrates from the carboxyl group to the amino group, leaving an ion with both a (+) and a (-) charge. 6 The Zwitterion This dipolar ion form is known as a Zwitterion. 7 Proteins- Levels of Structure Amino acids can undergo condensation reactions in any order, thus making it possible to form large numbers of proteins. Structurally, proteins can be described in four ways. 1. Primary 2. Secondary 3. Tertiary 4. Quaternary structure. 8 Primary Structure The primary structure of a protein is defined by the sequence of amino acids, which form the protein. This sequence is determined by the base pair sequence in the DNA used to create it. The sequence for bovine insulin is shown below 9 Secondary Structure The secondary structure describes the way that the chain of amino acids folds itself due to intramolecular hydrogen bonding Two common secondary structures are the a-Helix and the b- sheet 10 Tertiary Structure The tertiary structure maintains the three dimensional shape of the protein. The amino acid chain (in the helical, pleated or random coil form) links itself in places to form the unique twisted or folded shape of the protein. 11 Quaternary Structure Many proteins are not single strands The diagram below shows the quaternary structure of an enzyme having four interwoven amino acid strands 12 ISOELECTRIC POINT Amino acids in the zwitterion form are amphoteric. That is, they react readily with acids or bases. The reaction with bases converts the ammonium group into an amino group. The reaction with acids converts the carboxylate group into a carboxyl group. 13 In acidic solutions, amino acids exist as positive ions and are attracted toward the cathode. In basic solutions, amino acid exist as negative ions and are attracted toward the anode. At a certain ph amino acid would not migrate to either electrode and exist as neutral zwitterions. This ph is called isoelectric point. The isoelectric point is ph at which an amino acid exists completely as zwitterion. Each amino acid has a characteristic isoelectric point. Proteins which are composed of amino acids, also have characteristic isoelectric points. The migration under varying conditions of ph and electric field, is used to identify and separate amino acids from mixtures. RIBONUCLEIC ACID (RNA) This nucleic acid exists as a single standard helix. The structure of RNA is similar to that of DNA except that the sugar in it is ribose sugar and uracil is present instead of thymine has a heterocyclic base. There are three types of RNA, namely messenger, transfer, and ribosomal. The DNA and RNA are involved in protein biosynthesis, which involves two important processes of transcription and translation. DEOXRYRIBONUCLEIC ACID (DNA) Watson and Crick postulated that this nucleic acid has a double herical structure. In DNA, the sugar is a deoxyribose sugar and heterocyclic bases are adenine (A), guanine (G), thymine (T) and cytosine (C). The nucleotide chain in DNA has alternate sugar and phosphate ester residues. The phosphoric acid on one side forms ester linkage with 3’ –OH of one Sugar and on other side it forms ester linkage with 5’ –OH another sugar residue. The helix are held together by hydrogen bonds between the bases on one strand and those on the other. the bases in one strand are attached to complementary bases on other strand through hydrogen bonding. Adenine pairs with thymine while cytosine pairs up with guanine. The adenine and thymine base pairs have two hydrogen bonds between them while cytosine and guanine base pairs have three hydrogen bonds between them. Thus, two strands can fit together as a helix properly only if given base in one chain has only a Specific base as its nearest neighbour in the other chain.