Amino acids sequence in proteins

Role of the Amino Acid Sequence in Protein Structure Secondary Structure in Protein.s Protein Folding and Tertiary Structure Subunit Interaction.s and Quaternary Structure... 

Role of the Amino Acid Sequence in Protein Structure... 

Edman degradation A method of amino acid sequencing in proteins in which successive V-terminal amino acids are removed from the polypeptide chain and identified. 

Signal sequence Amino acid sequence in protein, whose function is to direct its final intracellular or exh acellular location. 

Eng J.K., McCormack A.L., and Yates J.R. (1994), An approach to correlate tandem mass spectral data of peptides with amino acid sequences in protein database, J. Am. Soc. Mass Spectrom. 5, 976-989. 

The single-letter abbreviations are often used to indicate amino acid sequences in proteins. 

Two major discoveries in 1953 were of crucial importance in the history of biochemistry. In that year James D. Watson and Francis Crick deduced the double-helical structure of DNA and proposed a structural basis for its precise replication (Chapter 8). Their proposal illuminated the molecular reality behind the idea of a gene. In that same year, Frederick Sanger worked out the sequence of amino acid residues in the polypeptide chains of the hormone insulin (Fig. 3-24), surprising many researchers who had long thought that elucidation of the amino acid sequence of a polypeptide would be a hopelessly difficult task. It quickly became evident that the nucleotide sequence in DNA and the amino acid sequence in proteins were somehow related. Barely a decade after these discoveries, the role of the nucleotide... 

Simplicity argues that the genetic blueprint specifying amino acid sequences in proteins should consist of consecutive, nonoverlapping triplets. This assumption turned out to be correct, as is illustrated by the DNA sequence for a gene shown in Fig. 5-5. In addition to the codons that determine the sequence of amino acids in the protein, there are stop codons that tell the ribosomal machinery when to terminate the polypeptide chain. One methionine codon serves as an initiation codon that marks the beginning of a polypeptide sequence. One of the valine codons sometimes functions in the same way. 

INTRON A region of a gene (i.e., ENA) that is transcribed in the synthesis of RNA, but enzymatically removed (by "splicing") from the final mRNA before its translation into an amino acid sequence in protein introns are characteristic of gene structure in eukaryotic, but not prokaryotic, cells. (See also EXON and CODING SEQUENCE)... 

In vitro determination of specific antigens in products using classical physicochemical and biochemical methods, which rely on the determination of amino acid sequences in proteins and their tertiary structure (see Section 3.4) as well as immunodetection methods using commercially available analytical tests... 

First the general structure and chemistry of the amino acids is presented. Then several methods that can be used to prepare them in the laboratory are discussed. After an introduction to the structure of peptides and proteins, chemical methods that can be used to determine the amino acid sequence in proteins are presented. Next, the synthesis of peptides in the laboratory is introduced. Finally, the three-dimensional structure of proteins and the mechanism of action of enzymes are briefly addressed. 

Zimmerman JM, Eliezer N, Simha R. The characterization of amino acid sequences in proteins by statistical methods. J. Theor. Biol. 1968 21 170-201. 

The analysis of disubstituted diketopiperazines [11] and/or disubstituted pyrrolidindiones [1] was also shown to provide information on the amino acid sequence in proteins. Compounds as those indicated below show the presence of specific amino acids pairs in the protein. 

Use Alkylating agent, reagent in elucidating amino acid sequence in proteins. 

An instrument which operates on the phenyl isothiocyanate degradation scheme has been developed for the automatic determination of amino acid sequences in proteins and peptides.4... 

A FIGURE 4-21 Two-step decoding process for translating nucleic acid sequences in mRNA into amino acid sequences in proteins. StepD An aminoacyl-tRNA synthetase first couples a specific amino acid, via a high-energy ester bond (yellow), to either the 2 or 3 hydroxyl of the terminal adenosine in the... 

Although the studies of the rll region of the T4 chromosome established that genetic mapping could be carried to the level of individual nucleotides in the DNA, it was still necessary to prove a linear correspondence between the nucleotide sequence in the DNA and the amino acid sequence in proteins. This was accomplished by Yanofsky - and associates through study of the enzyme tryptophan synthase of... 

By the application of the methods described in this review the structure of a pure polypeptide containing thirty residues has been determined (p. 54) and there seems no reason why it should not be possible to work out the complete amino acid sequence in proteins which are as simple as insulin. How far it will be possible to apply these techniques to more complex proteins is difficult to say. The larger the polypeptide chains in a protein, the greater the necessity of isolating larger peptide breakdown products. Probably the chief need in this field is for techniques for the specific breakdown of proteins into larger peptides and for the fractionation of such peptides. Most of the more commonly studied proteins contain more than 300 residues but it is possible that some of them, when studied in greater detail may be found to have a simpler structure than is at present believed. The relative simplicity of insulin may be merely apparent as insulin has been studied in more detail than have other proteins. 

Such a protein is more likely to pass through the intestinal wall into the bloodstream, where it can interact with cells of the immune system. Specific amino acid sequences in proteins that cause allergic reactions have also been identified, and these are catalogued in data banks. This allows researchers to compare them to amino acid sequences in novel proteins that are introduced into foods. 

The above analysis describes the role of hydrolysis in the natural selection of the amino acid sequence in protein synthesis at the level of the translational process. The other essential ingredient in the biochemical chain is DNA replication, by which DNA is synthesized within the cell. This process consists of the following critical steps ... 

The huge number of variations of amino acid sequences in protein molecules and variety of attached prosthetic groups result in an extraordinary diversity of proteins that differ in electric charge, size, shape, specific binding capabilities, and, consequently, in electrophoretic mobilities, which allows their separation using different electrophoretic... 

Transcription. Transcription is the process by which the genetic code stored in the DNA is transcribed to make RNA. This can be messenger RNA (mRNA Chapters 66 and 67), transfer RNA (tRNA Chapter 68) or ribosomal RNA (rRNA Chapter 69). mRNA contains the coded instructions for the amino acid sequence in proteins. It should be noted that in eukaryotes only 2% or less of the DNA is informational (i.e. genes). The rest has structural, regulatory and protective functions, or may be just junk . 

Gene duplication and independent evolution of the newly formed gene copies are also the molecular basis for the derivation of new secondary pathways from already existing ones. This can be shown by comparison of amino acid sequences in protein-derived secondary products with related chemical structures and by comparison of the nucleotide sequences in the corresponding genetic material. 

Dyads and triads in copolymers Free radical polymerization Geometric distribution Dyads and triads in terpolymers Nncleotide sequences in DNA Amino acid sequences in protein Sequence alignment... 

Nucleic Acids, DNA Replication, and Protein Synthesis Nucleic acids, including DNA and RNA, are polymers of nucleotides. In DNA, each nucleotide contains one of four bases adenine (A), cytosine (C), thymine (T), and guanine (G). The order of these bases contains a code that specifies the amino acid sequence in proteins. A codon, a sequence of three bases, codes for an amino acid. A gene, a sequence of hundreds to thousands of codons, codes for a protein. Genes are contained in cellular structures called chromosomes. 

Genetic information is contained in DNA whose base sequences in genes determine the amino-acid sequences in proteins. We already discussed why the coding unit in DNA was probably a group of three successive nucleotides (triplet). 

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