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Topic: Quaternary structure

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  Protein structure - Wikipedia, the free encyclopedia
Quaternary structure: the shape or structure that results from the union of more than one protein molecule, usually called protein subunits in this context, which function as part of the larger assembly or protein complex.
Protein structural motifs often include loops of variable length and unspecified structure, which in effect create the "slack" necessary to bring together in space two elements that are not encoded by immediately adjacent DNA sequences in a gene.
Within a protein, a structural domain ("domain") is an element of overall structure that is self-stabilizing and often folds independently of the rest of the protein chain.
en.wikipedia.org /wiki/Protein_structure   (2042 words)

 [No title]   (Site not responding. Last check: 2007-11-06)
Contiguous high densities within the 3D structure indicate a two-fold symmetry for this dimeric membrane receptor, as well as a logical sequence for its biochemical subdomains from the observed binding of a single insulin on the ectodomain to the juxtaposition of the pair of intrinsic tyrosine kinases (TKs) of the intracellular domain.
Another aspect of the invention is to use the structure coordinates of an insulin receptor to solve the structure of a different insulin receptor or a mutant, homologue or co-complex of insulin receptor.
The 3D structure of IR may be used to determine the 3D structure of these receptors by identifying regions of homology (similarity between amino acid, secondary, tertiary or quaternary structure) between the receptors and determining the structure of the dimeric receptor.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=00/73793.001207&ELEMENT_SET=DECL   (10104 words)

 Biophysical Journal: Open Interface and Large Quaternary Structure Movements in 3D Domain Swapped Proteins: Insights ...   (Site not responding. Last check: 2007-11-06)
Cristallographic investigations have revealed that these dimers display completely different quaternary structures: one dimer (N-dimer), which presents the swapping of the N-terminal helix, is characterized by a compact structure, whereas the other (C-dimer), which is stabilized by the exchange of the C-terminal end, shows a rather loose assembly of the two subunits.
Indeed, a survey of the quaternary structures of the other 3D domain swapped dimers shows that large variations are often observed when the structural determinations are conducted in different experimental conditions.
The 3D domain swapping phenomenon coupled with the high flexibility of the quaternary structure may be relevant for protein-protein recognition, and in particular for the pathological aggregations.
www.findarticles.com /p/articles/mi_qa3938/is_200503/ai_n13488234   (1327 words)

 Proteins   (Site not responding. Last check: 2007-11-06)
The primary structure of a segment of a polypeptide chain or of a protein is the amino-acid sequence of the polypeptide chain(s), without regard to spatial arrangement (apart from configuration at the alpha-carbon atom).
The quaternary structure of a protein molecule is the arrangement of its subunits in space and the ensemble of its intersubunit contacts and interactions, without regard to the internal geometry of the subunits (IUPAC-IUB, 1970).
An intermediate compact structure known as the molten globule which is different from the native structure and whose formation is determined mainly by non-specific interactions of amino acid residues with their environment was presented.
www.friedli.com /herbs/phytochem/proteins.html   (11287 words)

 Untitled Document
In deoxyhemoglobin the quaternary structure is such that a relatively large central cavity is formed between the four subunits.
When oxygen binds to the hemes, there is a relatively small conformational change in the tertiary structure of each subunit which results in a larger change in the interactions between the individual subunits (i.e the quaternary structure), narrowing the central cavity.
This is a crucial factor in the ability of hemoglobin to bind oxygen in the lungs and to release it in the tissues.
ase.tufts.edu /biology/MolecVisual/bio13/rightB13hemo.html   (666 words)

 Biology 403: Protein Structure
Tertiary structure is less crucial to our understanding of fibrous proteins, for which a description of the secondary structure often enables us to make sense of the protein's function.
Quaternary structure is the organization of multiple polypeptide chains into a functional whole.
Structural biologists produce protein crystals by purifying a protein and concentrating it, typically to concentrations somewhat higher than any single protein is present in the cytosol.
www.csrri.iit.edu /~howard/biol403/proteinstructure.html   (3962 words)

Primary structure of proteins: sequence of amino acids in the peptide.
Tertiary structure of proteins: the twisting, bending and coiling of the -helices due to ionic attractions, H-bonding.
Quaternary structure of proteins: large superstructures resulting from the aggregation of subunits made up of the coiled, bent alpha-helices.
virtual.parkland.edu /btreadway/102suplc.htm   (837 words)

 [No title]
A good example of proteins with well-defined domain structure are the immunoglobulins, the antibody proteins which circulate in the blood and combine with and neutralise foreign antigens.
The structure of lactoferrin, an iron binding protein from milk, was determined here at Massey by Professor Ted Baker and his group.
The structure shown is that of the protein from human milk.
www.massey.ac.nz /~wwbioch/Prot/fourths/quatext.htm   (982 words)

 Golbular Protein
The tertiary structure is such that it forms a "box-like" structure around heme.
The structure for hemoglobin is very similar to myoglobin except that it has a quaternary structure due to the presence of four protein chain subunits.
There are some changes in the structure of the deoxyhemoglobin when oxygen reacts to form oxyhemoglobin which is shown in the graphics on the left.
www.elmhurst.edu /~chm/vchembook/568globularprotein.html   (829 words)

 Quaternary structure   (Site not responding. Last check: 2007-11-06)
The geometry of the molecule is its quaternary structure.
The forces that stabilise a quaternary structure are much the same as those that stabilise the secondary and tertiary structure i.e.
The tertiary structure has a pleated sheet core (through centre), and when it forms a dimer, the two subunits stack back to back on each other in such a way that the pleated sheet is continued from one subunit to the other.
www-biol.paisley.ac.uk /courses/stfunmac/glossary/quaternary.html   (764 words)

 Aldolase and Quaternary Structure   (Site not responding. Last check: 2007-11-06)
In both mutant enzymes the loss of quaternary structure is commensurate with a loss in thermal stability and provides evidence that thermal stability, for aldolase, is one major role of the quaternary structure.
Ultracentrifugation of small volumes under controlled temperatures for the appraisal of quaternary structure and measuring the effect of temperature on the association/disassociation equilibrium are being done.
Stability of quaternary structure of mammalian and avian fructose diphosphate aldolases.
www.bu.edu /aldolase/lab/projects/quaternary.html   (248 words)

 [No title]
Primary structure, secondary structure, tertiary structure and quaternary structure.
I decided to use this particular protein to illustrate another basic concept namely that structures inside of cells are made of supermolecular assemblies.
Quaternary structure happens when two or more protein subunits join together to make a larger protein.
staff.jccc.net /pdecell/biochemistry/tubulin/tubulin.html   (574 words)

 Dr Chromo's school: protein structure and diversity
The primary structure of a protein is its amino acid sequence and the disulphide bridges, i.e.
The tertiary structure (or conformation) is the way random coils, alpha -helixes and beta -pleated sheets fold in respect to each other, ie it refers to the protein as a whole.
The quaternary structure is the arrangement of polypeptide subunits within complex proteins made up of two or more subunits, sometimes associated with non proteic groups.
www.rothamsted.bbsrc.ac.uk /notebook/courses/guide/prot.htm   (541 words)

Tertiary structure refers to the complete three-dimensional structure of the polypeptide units of a given protein.
Structural complexes involving protein associated with lipid via noncovalent interactions are termed lipoproteins.
This change of a single amino acid alters the structure of hemoglobin molecules in such a way that the deoxygenated proteins polymerize and precipitate within the erythrocyte, leading to their characteristic sickle shape.
www.med.unibs.it /~marchesi/proteins.html   (1338 words)

 Tertiary Structure
The tertiary structure of a protein is a description of the complex and irregular folding of the peptide chain in three dimensions.
These complex structures is held together by a combination of several molecular interactions that involve the R-groups of each amino acid in the chain.
The secondary, tertiary and quaternary structures, and therefore the activity, of a protein are as a direct result of the primary structure.
www.austincc.edu /~emeyerth/tertiary.htm   (1859 words)

 Sliding-layer conformational change limited by the quaternary structure of plant RuBisCO
structure, where L is the large catalytic subunit and S is the small subunit of unknown function.
The structure shows that all eight L subunits are elongated along the 4-fold axis so that the molecule cannot be simply described as layers of subunits, as it had been from studies by electron microscopy
The structure, with its elongated and inter-digitated L subunits, is evidence against a large, sliding-layer conformational change in plant RuBisCO, as proposed recently in Nature for the same enzyme from Alcaligenes eutrophus
www.nature.com /nature/journal/v329/n6137/abs/329354a0.html   (382 words)

 Structure of Mycobacterium tuberculosis Singlestranded DNA-binding Protein. Variability in Quaternary Structure and Its ...
The structure of one of the forms was solved by a combination of isomorphous replacement and anomalous scattering.
This quaternary structure with a unique dimeric interface lends the oligomeric protein greater stability, which may be of significance to the functioning of the protein under conditions of stress.
Also, as a result of the variation in the quaternary structure the path adopted by the DNA to wrap around MtuSSB is expected to be different from that of EcoSSB.
eprints.iisc.ernet.in /archive/00002113   (282 words)

 Quaternary structure (from protein) --¬† Encyclop√¶dia Britannica
The nature of the quaternary structure is demonstrated by the structure of hemoglobin.
Social structure is often treated together with the concept of social change, which deals with the forces that change the social structure and the organization of society.
This sequence, known as its primary structure, determines the shape and function of the protein.
www.britannica.com /eb/article-72529?tocId=72529   (824 words)

Strong evidence of repeated late Quaternary movement exists along the northern and central sections of the Williams Fork Mountains fault, a northwest-trending, east-dipping, normal fault along the western margin of the graben.
Conclusive evidence of late Quaternary activity on the southern end of the Williams Fork Mountains fault and on the Neogene fault that forms the eastern margin of the graben was not discovered during our reconnaissance.
Preliminary analysis of late Quaternary scarps along the Williams Fork Mountain fault involved measuring numerous profiles across the scarps and evaluation of pedogenic soils exposed in pits excavated into faulted deposits in the footwall of the structure.
gsa.confex.com /gsa/2003RM/finalprogram/abstract_52882.htm   (507 words)

 Proteins - Quaternary Structure   (Site not responding. Last check: 2007-11-06)
Quaternary structure refers to the association of multiple individual protein chains into a single protein with multiple subunits.
The arrangement of the subunits gives rise to a stable structure, which can usually be dissociated in the laboratory, but is very strongly bound in vivo.
The structure is a tetramer, with each subunit contributing two helices.
chemistry.umeche.maine.edu /CHY431/Proteins12.html   (377 words)

 Review: Protein Structure
A domain with a particular structure and function may be part of the structure of several otherwise distinct proteins.
For example, an enzyme's primary structure may include a segment that folds to produce an active site with particular catalytic activity, plus other segments that may mediate regulation of the enzyme or binding of the enzyme to a membrane.
Quaternary structure tends to be stabilized mainly by weak interactions between residues exposed on surfaces polypeptides within a complex.
www.rpi.edu /dept/bcbp/molbiochem/MBWeb/mb1/part2/protein.htm   (1123 words)

 BioBM 631 Lecture Oct-2-95   (Site not responding. Last check: 2007-11-06)
The formation of quaternary structure primarily involves noncovalent interactions between protein surfaces.
Examples that we have seen so far include a) the Greek Key motif which is found on Ramada Inn bathmats, Greek pottery, and as a form of protein supersecondary structure, and b) the similarity between coiled coils and strands of rope, where the strength of the resulting fiber is increased by coiling individual strands together.
Although the subunits are chamically identical, they pack in the icosahedron in such a way that the local environment of each subunit is not the same, and symmetrical packing is achieved through conformational adaptation of the subunits to their environment.
www.mbg.cornell.edu /nicholson/biobm631/struct_levels/quaternary/quaternary.html   (1605 words)

 Tertiary Structure
Davies) represent the tertiary structure of the antigen-binding portion of an antibody molecule.
Where the entire protein or parts of a protein are exposed to water (e.g., in blood or the cytosol), hydrophilic R groups — including R groups with sugars attached [Link] — are found at the surface; hydrophobic R groups are buried in the interior.
A mutation in the gene encoding a protein is a frequent cause of altered tertiary structure.
users.rcn.com /jkimball.ma.ultranet/BiologyPages/T/TertiaryStructure.html   (800 words)

That structure, in turn, determines the function of the proteins, that is, what role the protein plays in the living thing.
We will look at how some proteins are formed from the interconnection of two or more amino acid chains in what we call quaternary structure.
The molecule is the same but the orientation of the functional groups has been altered to make it easier to show how amino acids bond to one another to make peptides.
dl.clackamas.cc.or.us /ch106-08/structur.htm   (315 words)

 Quaternary Structure Index
In this chapter we study the units of biological structures which are composed of assemblies of individual elements of tertiary structure.
Quaternary Structure is that level of form in which units of tertiary structure aggregate to form homo- or hetero- multimers.
Identify the mutation in the structure and develop the causal explanation.
www.rpi.edu /dept/chem-eng/Biotech-Environ/Ryan/quaternary.html   (742 words)

 3.4 Primary through Quartenary structure   (Site not responding. Last check: 2007-11-06)
A protein's primary structure is simply the order of its amino acids.
The CO group of one amino acid (n) is hydrogen bonded to the NH group of the amino acid four residues away (n +4).
Quartenary structure is only present if there is more than one polypeptide chain.
web.mit.edu /esgbio/www/lm/proteins/structure/structure.html   (512 words)

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