Structure, primary tertiary

The example given is a primary amine (RNH2) Secondary amines have the general structure R2NH tertiary amines are R3N... 

Proteins have four levels of structure. Primary structure describes a protein s amino acid sequence secondary structure describes how segments of the protein chain orient into regular patterns—either a-helix or /3-pleated sheet tertiary structure describes how the entire protein molecule coils into an overall three-dimensional shape and quaternary structure describes how individual protein molecules aggregate into larger structures. 

Each protein has a unique three-dimensional shape called its tertiary structure. The tertiary structure is the result of the bends and folds that a polypeptide chain adopts to achieve the most stable structure for the protein. As an analogy, consider the cord in Figure 13-39 that connects a computer to its keyboard. The cord can be pulled out so that it is long and straight this corresponds to its primary structure. The cord has a helical region in its center this is its secondary structure. In addition, the helix may be twisted and folded on top of itself This three-dimensional character of the cord is its tertiary structure. 

C(C=0)C1 group to the precise structure (primary, secondary or tertiary) of the alkyl groups to which it is linked. However, our subsequent work with NO showed that its products are also sensitive to the alkyl structure yet in addition NO reacts with oxidized polymers to give distinctly different products from alcohol and hydroperoxide groups (see below). Consequently the COCl2 products were not explored further. 

Figure 1.3 Folding of a polypeptide chain illustrating the hierarchy of protein structure from primary structure through secondary structure and tertiary structure.

All proteins have at least three levels of structure primary, secondary, and tertiary. Proteins with more than one polypeptide chain— hemoglobin and nitrogenase are examples—also possess quaternary structure. The primary. 

Christian Anfinsen did the crucial experiment that showed that primary structure determines tertiary structure for proteins C. J. Epstein, R. F. Goldberger, and C. B. Anfinsen, Cold Spring Harbor Symp Quant Biol 28 439 (1963). This experiment is not always as simple... 

We generally describe the structure of both synthetic and natural polymers in terms of four levels of structure primary, secondary, tertiary, and quaternary. The primary structure describes the precise sequence of the individual atoms that compose the polymer chain. For polymers that have only an average structure, such as proteins, polysaccharides, and nucleic acids, a representative chain structure is often given. 

DIMS Primary structure 5-3 Major secondary structure Major tertiary structure (%) IFNa IFNp IFNy... 

Silver halide precipitates at a rate that depends upon the structure of the alkyl group, tertiary > secondary > primary. Tertiary halides usually react immediately at room temperature, whereas primary halides require heating. That complexes actually are formed between organic halides and silver ion is indicated by an increase in water solubility in the presence of silver ion for those halides that are slow in forming carbocations. 

The distinction between secondary and tertiary structure is not sharp. Secondary structure involves consideration of the interactions and spatial relationships of the amino acids in the peptide chains that are close together in the primary structure, whereas tertiary structure is concerned with those that are-far apart in the primary structure. 

The structure of proteins, as with the structure of carbohydrates, has various levels—primary, secondary, tertiary and quaternary structure. The tertiary and quaternary structures and their subtleties are most important in the biological function of the molecule. Consider an enzyme (a protein-based catalyst)—its structure allows the binding of specific molecules which then react catalytically to give products. Conversely, enzymes are very susceptible to environmental conditions which alter their tertiary structure. 

Visualizing Folded Protein Structures Primary Structure Determines Tertiary Structure Secondary Valence Forces Are the Glue That Holds Polypeptide Chains Together Domains Are Functional Units of Tertiary Structure Predicting Protein Tertiary Structure Quaternary Structure Involves the Interaction of Two or More Proteins... 

Sequence analysis is a core area of bioinformatics research. There are four basic levels of biological structure (Table 1), termed primary, secondary, tertiary, and quaternary structure. Primary structure refers to the representation of a linear, hetero-polymeric macromolecule as a string of monomeric units. For example, the primary structure of DNA is represented as a string of nucleotides (G, C, A, T). Secondary structure refers to the local three-dimensional shape in subsections of macromolecules. For example, the alpha- and beta-sheets in protein structures are examples of secondary structure. Tertiary structure refers to the overall three-dimensional shape of a macromolecule, as in the crystal structure of an entire protein. Finally, quaternary structure represents macromolecule interactions, such as the way different peptide chains dimerize into a single functional protein. 

Alcohols can be regarded as hydroxyl derivatives of hydrocarbons. They can be characterized by the number of hydroxyl groups (monohydric, dihydric, etc.), according to their structure (primary, secondary or tertiary), and by the structure of the hydrocarbon function to which the hydroxyl is attached (aliphatic, cyclic, saturated or unsaturated). 

Figure 11,4. ExPASy Proteomic tools. ExPASy server provides various tools for proteomic analysis which can be accessed from ExPASy Proteomic tools. These tools (locals or hyperlinks) include Protein identification and characterization, Translation from DNA sequences to protein sequences. Similarity searches, Pattern and profile searches, Post-translational modification prediction, Primary structure analysis, Secondary structure prediction, Tertiary structure inference, Transmembrane region detection, and Sequence alignment.

Chirality Isomerism Lewis Structures Magnetism Molecular Geometry Molecular Modeling Molecular Structure Molecules Periodic Table Primary Structure Quaternary Structure Secondary Structure Stoichiometry Tertiary Structure... 

Q Show how you would use solution-phase synthesis or solid-phase synthesis to make a given peptide. Use appropriate protecting groups to prevent unwanted couplings. Q Discuss and identify the four levels of protein structure (primary, secondary, tertiary, and quaternary). Explain how the structure of a protein affects its properties and how denaturation changes the structure. Problems 24-44, 45, and 52... 

Among unsolvated organolithium compounds only the alkyllithiums are soluble in noncoordinating solvents such as alkanes and arenes. Their states of aggregation depend on the structure close to lithium. Thus primary, tertiary and secondary alkyllithiums, all unsolvated, assemble into respectively hexamers, tetramers and equilibrium mixtures of hexamers and tetramers. Most organolithium compounds dissolve in and coordinate with donor compounds such as ethers and tertiary amines. The actual structures depend critically on the nature of the donor. Thus, diethyl ether solvates tend to be mainly cubic tetramers (with some dimers) while THF favors mixtures of monomers and dimers. Tertiary vicinal diamines such as TMEDA and 1,2-di-Af-piperidinoethane, DPE, favor bidentated coordinated dimers. Finally, in the presence of triamines such as pentamethyl-triethylenediamine PMDTA and l,4,7-trimethyl-l,4,7-triazacyclononane TMTAN, many organolithium compounds form tridentately complexed monomers. 

Biochemically there are four major classifications of protein structure primary (amino acid sequence), secondary (local spatial arrangement), tertiary (overall 3D structure) and quaternary (protein complex stmcture). (Figure 1.8)... 

In describing protein structure it is usual to consider four levels of organization, termed primary, secondary, tertiary and quaternary structure. Primary structure refers to. the sequence of amino acids that makes up the chain of a particular protein (or synthetic polypeptide). Secondary structure is the ordered conformation that the chain (or usually parts of chains) can twist itself into. An example, a section of an a-helical chain is shown in Figure 9.9. More on this shortly. 

The primary stmcture gives rise to higher order levels of structure (secondary, tertiary, quaternary) and all enzymes have a three-dimensional folded structure of the polymer chain (or chains). This tertiary structure forms certain arrangements of amino acid groups that can behave as centers for catalytic reactions to occur (denoted as active sites). How an active site in an enzyme performs the chemical reaction is described in Vignette 4.2.1. 

Crystals of human insulin. Insulin is a protein hormone, crucial for maintaining blood sugar at appropriate levels. (Below) Chains of amino acids in a specific sequence (the primary structure) define a protein like insulin. These chains fold into well-defined structures (the tertiary structure) in this case a single insulin molecule. Such structures assemble with other chains to form arrays such as the complex of six insulin molecules shown at the far right (the quartemary structure). These arrays can often be induced to form well-defined crystals (photo at left), which allows determination of these structures in detail. [(Left) Alfred Pasieka/Peter Arnold.]... 

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