Sandbox Reserved 830: Difference between revisions
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OSM is a compact molecule with dimensions of approximately 20 Å x 27 Å x 56 Å, that fit with the up-up-down-down four-helix bundle structure. | OSM is a compact molecule with dimensions of approximately 20 Å x 27 Å x 56 Å, that fit with the up-up-down-down four-helix bundle structure. | ||
[[Image:Oncostatin structure.png|frame| | [[Image:Oncostatin structure.png|frame|right|Ribbon colored diagram of hOSM from N-terminus in blue to the C-terminus in red. The two disulphide bonds are shown as ball-and-sticks models with the sulphur atoms represented as yellow spheres. The CD loop as observed in LIF is represented by the transparent dotted section.]] | ||
OSM structure is composed of the four main α helical region (helix A, residues 10–37; helix B, residues 67–90; helix C, residues 105–131; helix D, residues 159–185) linked by two long overhand loops (AB loop, residues 38–66; CD loop, residues 130–158) and one short loop (BC loop, residues 91–104). Globally, OSM arrangement corresponds to A-D forming one pair of helices which is parallel to the B-C pair. | OSM structure is composed of the four main α helical region (helix A, residues 10–37; helix B, residues 67–90; helix C, residues 105–131; helix D, residues 159–185) linked by two long overhand loops (AB loop, residues 38–66; CD loop, residues 130–158) and one short loop (BC loop, residues 91–104). Globally, OSM arrangement corresponds to A-D forming one pair of helices which is parallel to the B-C pair. | ||
[[Image:Oncostatin structure2.png|frame|center|Stereodiagram of the Cα trace for hOSM.]] | |||
Helices A and C have breaks in the hydrogen-bonding pattern of their structure, forming tight substitute hydrogen bonds with water molecules. Indeed, it results in a kink in helix A (and slightly in helix C between residues Gln112 and Pro116) induced by a disruption in the helical conformation, due to the Gln25 and Leu30 hydrogen bonds with four water molecules. Helix A residues between Thr27 and Ile37 take on a 310 helix conformation. With this curved structure, helices A and C enhance the compaction of the A-D and B-C parallel helix pairs, causing the core of OSM to be isolated from the solvent. | Helices A and C have breaks in the hydrogen-bonding pattern of their structure, forming tight substitute hydrogen bonds with water molecules. Indeed, it results in a kink in helix A (and slightly in helix C between residues Gln112 and Pro116) induced by a disruption in the helical conformation, due to the Gln25 and Leu30 hydrogen bonds with four water molecules. Helix A residues between Thr27 and Ile37 take on a 310 helix conformation. With this curved structure, helices A and C enhance the compaction of the A-D and B-C parallel helix pairs, causing the core of OSM to be isolated from the solvent. | ||