Cellulose: Difference between revisions

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Karsten Theis

Revision as of 19:21, 24 August 2019 view source Karsten Theis (talk \| contribs) Macro 4,174 edits No edit summary ← Older edit		Revision as of 19:25, 24 August 2019 view source Karsten Theis (talk \| contribs) Macro 4,174 edits No edit summary Newer edit →
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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 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 tightly packed 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/3'>individual chains</scene> of cellulose form <scene name='82/824000/Chain/2'>layers</scene> held together by <scene name='82/824000/Hbonds/3'>hydrogen bonds</scene>, and <scene name='82/824000/Contacts/4'>multiple layers stack</scene> to form a 3D structure without any gaps.		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 tightly packed 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/3'>individual chains</scene> of cellulose form <scene name='82/824000/Chain/2'>layers</scene> held together by <scene name='82/824000/Hbonds/4'>hydrogen bonds</scene>, and <scene name='82/824000/Contacts/4'>multiple layers stack</scene> to form a 3D structure without any gaps.