Structure quarternary

Model peptides that could build up quarternary fibrillar structures are not yet known. Though complete explanation of the interdependence between the primary structure and the stability of the quarternary structure has not yet been possible, i.e. the role of the different amino acids in collagen could be understood completely only in correlation with the fibril formation (formation of polar and hydrophobic clusters ). 

Can the adducts and cross-links formed when formaldehyde reacts with proteins in solution be completely reversed under any circumstances Can they be reversed while preserving primary, secondary, tertiary, and quarternary structures ... 

The resolution of SAXS depends on the form of the molecule and is on average between 0.2 and 0.5 nm. The main difference from high resolution X-ray diffraction is that SAXS can resolve only details of the tertiary and quarternary structure of the molecule and thus give information about the molecular shape but not on the secondary structure. 

Structure of the Recognition Sequence and Quarternary Structure of DNA-binding Proteins... 

That is, we must learn how amino acid content and molecular configuration of food proteins are related to their functional properties. This goal is made more difficult by the fact that secondary, tertiary, and quarternary structures of proteins are likely to be quite different when exerting functional effects in food systems as compared to structures of the same proteins in dilute solutions and in their native states. The way in which specific actions of proteases affect protein structure must also be studied so that correlations with changes in functional properties can be made (61). 

The biochemistry of plant cell-walls is still at the stage of identifying and elucidating the covalent structures of the macromolecular components of the primary cell-wall. The secondary, tertiary, and quarternary structures of the polysaccharides therein have received only scant attention.29-32 The ultrastructural distribution of polymers within the wall, the integration of newly synthesized macromolecules into the wall, and... 

The influence of the effectors pyruvamide and phosphate on the quarternary structure of PDCS.c. has been demonstrated by X-ray solution scattering [113]. Whereas phosphate stabilizes the tetrameric structure, the addition of pyruvamide gave rise to a less compact tetramer, due to structural changes upon binding to the regulatory site (for a more detailed description of the substrate activation behaviour see Sects. 4.2 and 6.1). 

From Fig. 1 it can be seen that the highest activity for both soluble (0.0569 U/mL) and immobilized (0.0559 U/mL) invertase occurred at 55 and 50°C, respectively. As the maximal activities differed <2%, one can assume that the immobilization procedure did not significantly affect the tertiary and quarternary structures of the invertase. 

The secondary structures are combined with specific geometric arrangement to form compact globular structure known as tertiary structure. The fundamental unit of tertiary structure is the domain, which is defined as a polypeptide chain or a part of a polypeptide chain that can independently fold into a stable tertiary structure (Murphy, 2001). Domains are also units of function, and often the different domains of a protein are associated with different functions. Polypeptide chains, especially of regulatory proteins, often aggregate by specific interactions to form oligomeric structures. These oligomeric proteins are said to exhibit quarternary structure. The association of proteins with other biomacromolecules to form complexes of cellular components is referred to as quinternary structure. 

It is a homobifunctional, noncleavable reagent, which has been in use as a crosslinker since 1970 and is commonly used in determining the quarternary structure of proteins... 

Protein - max A Quarternary structure Bilin content per subunit Bilin binding positions Number of residues % Homology between ap-subunits Refs. 

M Bianchet, X Isern, J Hullihen, PL Pedersen and LM Amzel (1991) Mitochondrial ATP synthase - quarternary structure of the F moiety at 3.6 determined by X-ray diffraction analysis. J Biol Chem 266 21197-21201... 

H Tiedge, G Sch fer and F Meyer (1983) An electron microscopy approach to the quarternary structure of mitochondrial F, ATPase. Eur J Biochem 132 37-45... 

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 such as 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 quarternary structure). These arrays can often be induced to form well-defined crystals (photograph at left), which allows determination of these structures in detail, [Photograph from Alfred Pasieka/Peter Arnold.]... 

The secondary structure types are the a-helix, p-sheet, and p-turn. The tertiary structure groups are the overall shape of a single protein molecule the spatial relationship of structures to one another. The term tertiary structure is often used as synonymous with the term fold, the shape or structure that results from the interaction of more than one protein molecule, usually called protein subunits in this context, which function as part of the larger assembly or protein complex. The quarternary structure the shape or structure that results from the nteraction of more than one protein molecule, usually called protein subunits in this context, which function as part of the larger assembly or protein complex. 

Proteins are composed of an amino acid backbone which defines their primary structure. The amino acid side chains hydrogen-bond to each other, creating areas of local order such as a helices and (3-pleated sheets. These types of arrangement are known as secondary structure. The overall folding of the molecule, which defines its three-dimensional shape, is known as the tertiary structure. Finally, some proteins, such as haemoglobin, are composed of more than one subunit the spatial arrangement of these subunits is known as the quarternary structure. 

The structure of these proteins is often described according to levels called primary, secondary, tertiary, and quaternary structure (see Fig. 7.1). The primary structure is the linear sequence of amino acid residues joined through peptide bonds to form a polypeptide chain. The secondary structure refers to recurring structures (such as the regular structure of the a-helix) that form in short localized regions of the polypeptide chain. The overall three-dimensional conformation of a protein is its tertiary structure. The quarternary structure is the association of polypeptide subunits in a geometrically specific manner. 

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