Cellulose
From Proteopedia
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Longer chains of beta 1,4 linked glucoses are found in cellulose. When cellulose is synthesized, these chains are made individually (cellulose chain during <scene name='82/824000/Cellulose/2'>biosynthesis</scene>). Again, the linkages are all of the beta 1,4 type (<jmol><jmolLink><script> select *.C1; selectionHalos ON; delay 0.5;selectionHalos OFF;</script><text>☼</text></jmolLink> </jmol>). In this structure, monomers are added to polymer chain inside the cell and secreted through the membrane, surrounded by the <scene name='82/824000/Cellulose/4'>enzyme</scene> throughout. | Longer chains of beta 1,4 linked glucoses are found in cellulose. When cellulose is synthesized, these chains are made individually (cellulose chain during <scene name='82/824000/Cellulose/2'>biosynthesis</scene>). Again, the linkages are all of the beta 1,4 type (<jmol><jmolLink><script> select *.C1; selectionHalos ON; delay 0.5;selectionHalos OFF;</script><text>☼</text></jmolLink> </jmol>). In this structure, monomers are added to polymer chain inside the cell and secreted through the membrane, surrounded by the <scene name='82/824000/Cellulose/4'>enzyme</scene> throughout. | ||
| - | Once secreted, individual cellulose chains | + | Once secreted, individual cellulose chains self-assemble to from semi-crystalline cellulose micro-fibrils. There are multiple forms of cellulose (I alpha and beta, II, III) which differ in the orientation and the detailed interactions between linear polymers. A model of a <scene name='82/824000/Block/1'>cellulose type I beta micro-fibril</scene> shows how <scene name='82/824000/Single/1'>inter-chain hydrogen bonding and hydrophobic interactions</scene> lead to a highly ordered structure. The model was made using cellulose builder (http://cces-sw.iqm.unicamp.br/cces/admin/cellulose, <ref>DOI:10.1002/jcc.22959</ref>) and is based on a fiber-diffraction study by Nishiyama et al <ref>DOI:10.1021/ja0257319</ref>. The <scene name='82/824000/Chain/1'>individual chains</scene> of cellulose form <scene name='82/824000/Chain/2'>layers</scene> held together by <scene name='82/824000/Hbonds/1'>hydrogen bonds</scene>, and <scene name='82/824000/Contacts/4'>multiple layers stack</scene> to form a 3D structure without any gaps. |
Revision as of 16:09, 24 August 2019
Cellulose is the most abundant biopolymer on earth. It occurs in plant cell walls and in bacteria. Common materials containing high amounts of cellulose are wood, paper, and cotton. Cellulose is a water-insoluble polysaccharide that humans can not digest. It is a linear polymer of beta-1,4 linked glucose building blocks, with chains arranged in microfibrils held together by hydrogen bonds and hydrophobic interactions. Cellulose is related to but distinct from starch, a water-soluble carbohydrate containing alpha-1,4 linked glucose building blocks that is digestible by humans.
Structure
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See also
LEcture slides by Eero Kontturi, Aalto University, Espoo, Finland: https://mycourses.aalto.fi/pluginfile.php/148341/mod_folder/content/0/Lecture%202%20-%20Cellulose%20structure.pdf?forcedownload=1
References
- ↑ Gomes TC, Skaf MS. Cellulose-builder: a toolkit for building crystalline structures of cellulose. J Comput Chem. 2012 May 30;33(14):1338-46. doi: 10.1002/jcc.22959. Epub 2012 Mar , 15. PMID:22419406 doi:http://dx.doi.org/10.1002/jcc.22959
- ↑ Nishiyama Y, Langan P, Chanzy H. Crystal structure and hydrogen-bonding system in cellulose Ibeta from synchrotron X-ray and neutron fiber diffraction. J Am Chem Soc. 2002 Aug 7;124(31):9074-82. doi: 10.1021/ja0257319. PMID:12149011 doi:http://dx.doi.org/10.1021/ja0257319
