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Topic: Alpha helix


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In the News (Mon 17 Jun 19)

  
  Alpha helix - Wikipedia, the free encyclopedia
Short polypeptides usually are not able to adopt the alpha helical structure, since the entropic cost associated with the folding of the polypeptide chain is too high.
Ordinarily, a helix has a buildup of positive charge at the N-terminal end and negative charge at the C-terminal end which is a destabilizing influence.
This is because of a structural coincidence: The diameter of the α helix is 120 nm, the same as the width of the major groove in B-form DNA.
en.wikipedia.org /wiki/Alpha_helix   (376 words)

  
 Alpha helix   (Site not responding. Last check: 2007-10-21)
In protein s, the α helix is a major structural motif in secondary structure.
Short polypeptide s usually are not able to adopt the alpha helical structure, since the entropic cost associated with the folding of the polypeptide chain is too high.
Alpha Phi Alpha - Cincinnati, University of - Alpha Alpha Chapter History, Jewels, the "Double A Legacy", photo gallery, and Cabaret.
www.serebella.com /encyclopedia/article-Alpha_helix.html   (616 words)

  
 Alpha helix - Open Encyclopedia   (Site not responding. Last check: 2007-10-21)
In proteins, the α helix is a major structural motif in secondary structure.
Each amino acid results in a 100° turn in the helix, and corresponds to a translation of 1.5Å along the helical axis.
This is because of the structural coincidence of the α helix diameter of 12Å being the same as the width of the major groove in B-form DNA.
www.open-encyclopedia.com /Alpha_helix   (363 words)

  
 PPS 96' - Alpha-Helix Geometry Part. 2   (Site not responding. Last check: 2007-10-21)
The separation of residues along the helix axis is 5.4/3.6 or 1.5 Angstroms, ie the alpha-helix has a rise per residue of 1.5 Angstroms.
The peptide planes are roughly parallel with the helix axis and the dipoles within the helix are aligned, ie all C=O groups point in the same direction and all N-H groups point the other way.
Strictly, these form a distinct class of helix but they are always short and frequently occur at the termini of regular alpha-helices.
www.cryst.bbk.ac.uk /PPS2/course/section3/helix2.html   (489 words)

  
 Alpha helix   (Site not responding. Last check: 2007-10-21)
It was first postulated by Linus Pauling, Robert Corey, and Herman Branson in 1951 based on the known crystal structures of aminoacids and peptides and Pauling's prediction of planar peptide bonds.
Short polypeptides usually are not able to adopt the alpha helicalstructure, since the entropic cost associated with the folding of the polypeptidechain is too high.
Ordinarily, a helix has a buildup of positive charge at the N-terminal end and negative charge at the C-terminal end which isa destabilizing influence.
www.therfcc.org /alpha-helix-28505.html   (349 words)

  
 alpha helix   (Site not responding. Last check: 2007-10-21)
The alpha helix is the most abundant helical conformation found in globular proteins.The average length of an alpha helix is 10 residues.
The screw sense of alpha helices is always right-handed.Looking at the helix along the helical axis from the C-terminus (top), you can see the four carbonyl oxygens of the last turn of the helix and the dispersion of sidechains.
End caps are sidechain-to-backbone H-bonds between the sidechain of a residue just beyond the end of the helix and an otherwise unsatisfied backbone H-bonding group of a residue in the helix.
www.med.unibs.it /~marchesi/alpha.html   (312 words)

  
 Alpha Helix / Product pipeline
Alpha Helix intends to offer products enhancing and cutting time in all steps of the PCR process.
Alpha Helix has developed a technology to extract DNA from whole blood in less than 2 minutes.
Alpha Helix is currently developing a 0,2 ml reaction tube.
www.alphahelix.com /pages/pipeline.html   (162 words)

  
 UAF IMS: R/V Alpha Helix   (Site not responding. Last check: 2007-10-21)
The 133-foot research vessel Alpha Helix is an oceanographic ship operated by the University of Alaska's Institute of Marine Science for the National Science Foundation.
The Alpha Helix was formerly a national oceanographic facility at Scripps Institution of Oceanography in La Jolla, California, and was acquired in 1980 to replace the smaller vessel Acona, which had supported University of Alaska marine studies since 1964.
The Alpha Helix is maintained and used as a year-round platform supporting oceanographic research on the open ocean and in Alaska's shelf and coastal waters.
www.ims.uaf.edu /helix   (265 words)

  
 Alpha helix   (Site not responding. Last check: 2007-10-21)
It was first postulated by Linus Pauling, Robert Corey, and Herman Branson in 1951 based on the known crystallographycrystal structures of amino acids and peptides and Pauling's prediction of planar peptide bond/s.
The amino acids in an α helix are arranged in a helixhelical structure, about 1 E-10 m5 Å wide.
Short polypeptides usually are not able to adopt the alpha helical structure, since the entropyentropic cost associated with the folding of the polypeptide chain is too high.
www.infothis.com /find/Alpha_helix   (358 words)

  
 Gulf of Alaska, Aboard the Alpha Helix---This Ain't No Fishing Boat, Alaska Science Forum
The Alpha Helix is a ship dedicated to science, a floating lab for those who study chemistry, biology, physics or geology.
Instead of crab pots and floats, the Alpha Helix carries a $100,000 sea water sampler the size of a refrigerator, a series of fine nets to capture zooplankton and an elaborate fish finder.
Now 33 years old, the Alpha Helix is the annual recipient of the Order of the Ancient Albatross, signifying the oldest and longest-operating research vessel in the university national oceanographic laboratory system.
www.gi.alaska.edu /ScienceForum/ASF13/1381.html   (623 words)

  
 alpha_helix   (Site not responding. Last check: 2007-10-21)
The amino acids in an α helix are arranged in a helical structure, about 50 nm (5 �) wide.
Each amino acid results in a 100� turn in the helix, and corresponds to a translation of 15 nm along the helical axis.
This is because of the structural coincidence of the α helix diameter of 120 nm being the same as the width of the major groove in B-form DNA.
goc.subdomain.de /alpha_helix   (369 words)

  
 [2] Alpha Helix
helix can be either right-handed or left-handed, as defined in the following figure.
The right-handed or left-handed helix may be distinguished by stretching out your thumb and curling the other four fingers.
helix structure of CAP18, which is a molecule capable of binding to the endotoxin of bacteria.
www.web-books.com /mobio/free/Ch2C4.htm   (235 words)

  
 Alpha helix - Encyclopedia.WorldSearch   (Site not responding. Last check: 2007-10-21)
ISHTAR cruise report: R/V Alpha Helix cruise HX-072 : 12-24 July 1985
Journal of a return to the Kuru region and the Anga peoples of New Guinea and preliminary preparations for the research vessel Alpha Helix expedition to...
Cruise report R/V Alpha Helix Cruise-173 to western Prince William Sound, Yakutat Bay, and Glacier Bay National Park, northeastern Gulf of Alaska, August 17 - September 3, 1993 (SuDoc I 19.76:94-258)
encyclopedia.worldsearch.com /alpha_helix.htm   (514 words)

  
 beta-sheet pore
A dense core formed by a short alpha helix segment and several antiparallel beta-sheet stretches, maintained by disulfide pairing, seems to be a common structural feature present in all toxins.
A conformational change is postulated by which the helix pair C-D peels away from the sheet to lie on the membrane surface, while the sheet region rearranges to form an oligomeric trans-membrane pore.
The distinctive appearance of the alpha subunits in this region suggests that the rods may be involved in forming the binding pocket for acetylcholine.
lansbury.bwh.harvard.edu /beta_sheet_pore.htm   (15966 words)

  
 Alpha helix   (Site not responding. Last check: 2007-10-21)
The amino acids in an α helix are arranged in a helical structure, about 5 ?/a> wide.
Each amino acid results in a 100° turn in the helix, and corresponds to a translation of 1.5?along the helical axis.
This is because of the structural coincidence of the α helix diameter of 12?being the same as the width of the major groove in B-form DNA.
alpha-helix.en.exsugo.org   (349 words)

  
 FY02 Alpha Helix Replacement   (Site not responding. Last check: 2007-10-21)
This request is for federal funding to replace the Research Vessel Alpha Helix, operated by the University of Alaska Fairbanks (UAF), for the National Science Foundation.
The Alpha Helix, constructed in 1965, is the oldest vessel in the United States Fleet.
The Alpha Helix is specifically mentioned as having reached retirement age.
www.alaska.edu /federal/fedinit02/alphahelix.html   (409 words)

  
 Dr Chromo's School: the alpha - helix
If we represent the backbone structure (Diagram 2), we see that alpha carbons spaced three and four in the linear sequence are actually quite close together in an alpha - helix structure.
We concentrate on the residues 16 to 30 which are arranged in an alpha - helix.
Study an alpha - helix with RasMol: Pancreatic Hormone is a good example to look at.
www.rothamsted.bbsrc.ac.uk /notebook/courses/guide/protalpha.htm   (317 words)

  
 Alpha-Helix - Wikipedia
Die Aminosäure Prolin ("Strukturbrecher") lässt sich nicht ohne weiteres in die Helix einfügen (nur an den Positionen 1-4, vom Aminoende aus gesehen, ist dies möglich).
Deshalb findet man sie in der Darstellung von Proteinstrukturen nicht nur als Helix, sondern auch als Zylinder abgebildet.
Dies setzt amphipathische Helices voraus, das sind Helices deren eine Seite hydrophil (dem Wasser zugewandt) und deren andere Seite hydrophob und damit zu Wechselwirkungen befähigt ist.
de.wikipedia.org /wiki/Alpha-Helix   (900 words)

  
 BCH222-Helix Worksheet   (Site not responding. Last check: 2007-10-21)
In the central section (View2) where the H-bonding is regular, choose one helical H-bond: it is from the CO of residue _____ to the NH of residue _____ (that is, n to n+ _____).
This helix is membrane-active, and has a rather extreme segregation of charges and hydrophobics.
If the helix continued, the NH of residue 10 would bond back to the CO of 6 and the NH of 11 to the CO of 7 (normal n to n+4 pattern), but here NH 10 bonds to CO _____ and NH 11 to CO _____.
kinemage.biochem.duke.edu /teaching/bch222/helices/helix.wrksht.html   (1122 words)

  
 Polyalanine Alpha Helix   (Site not responding. Last check: 2007-10-21)
The alpha helix is a fundamental structural feature of many proteins.
The helix shown consists of 13 residues of alanine in a right-handed alpha helix.
The helix stucture is stabilised by hydrogen bonding between the alpha carbonyl oxygen of one amino acid residue and alpha amido proton on the fourth residue up the helix.
www.cf.ac.uk /biosi/vle/MOLMODEL/A-HELIX1.HTM   (85 words)

  
 Is Native DNA A Helix?   (Site not responding. Last check: 2007-10-21)
I have never doubted that the right-handed "double helix" is the structure of pure DNA in crystals, although there are some who doubt even this.
In any helix (or superhelix), the term "right-handed" means that if you hold it vertically, and imagine yourself standing in front of it, watching a little man climbing upwards, he will invariably be moving to the right each time he passes in front of you.
In a third moment, the helix may become slightly underwound--but never to the extent of the proposed underwinding of the native chromosome; only to the extent which is energetically possible with nothing to drive the winding-unwinding other than random motion of molecules in solution.
www.notahelix.com   (17824 words)

  
 Alpha helix   (Site not responding. Last check: 2007-10-21)
Ordinarily a helix has a buildup of charge at the N-terminal end and negative at the C-terminal end which is a influence.
As a result α helices are capped at the N-terminal end by a charged amino acid (like glutamic acid) in order to stabilise the helix Less common (and less effective) is C-terminal with a positively charged protein like lysine.
This is because of the coincidence of the α helix diameter of being the same as the width of major groove in B-form DNA.
www.freeglossary.com /Alpha_helix   (408 words)

  
 Alpha Helix   (Site not responding. Last check: 2007-10-21)
The backbone of an alpha helix (shown in color below) is arranged in a spiral similar to that seen on a cork screw.
The alpha helix is stabilized by hydrogen bonds between the carbonyl oxygen of one amino acid and the backbone nitrogen of a second amino acid located four positions away.
This alpha helix consists of residues 4 to 15 in
webhost.bridgew.edu /fgorga/proteins/alpha.htm   (108 words)

  
 Secondary Structure   (Site not responding. Last check: 2007-10-21)
The most common of these are the alpha helix and the beta conformation.
The helix is right-handed; it twists in a clockwise direction.
The carbonyl group (-C=O) of each peptide bond extends parallel to the axis of the helix and points directly at the -N-H group of the peptide bond 4 amino acids below it in the helix.
www.ultranet.com /~jkimball/BiologyPages/S/SecondaryStructure.html   (145 words)

  
 ninemsn Encarta - Protein
In the late 1930s, Linus Pauling and Robert Corey in the United States used x-ray diffraction (a technique in which a beam of X-rays is passed through a crystal of the substance and the scattered rays measured) to determine the structures of amino acids and peptides.
They also correctly predicted that many amino acid chains would fold into a stable conformation rather like a spiral staircase, now known as an a- (alpha-) helix.
Another milestone occurred in 1955 when the Cambridge scientist Fred Sanger chemically analysed insulin, a small protein hormone, and showed that it was built from a defined set of amino acids linked together in a unique linear sequence.
au.encarta.msn.com /encyclopedia_761565946/Protein.html   (1012 words)

  
 Role of Backbone Hydration and Salt-Bridge Formation in Stability of {alpha}-Helix in Solution -- Ghosh et al. 85 (5): ...
Helix propensities of the amino acids measured in alanine-based peptides without helix-stabilizing side-chain interactions.
Effect of a single aspartate on helix stability at different positions in a neutral alanine-based peptide.
Theory of the phase transition between helix and random coil in polypeptide chains.
www.biophysj.org /cgi/content/full/85/5/3187   (3537 words)

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