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 BGC and *.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 BGC and *.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 <scene name='82/824000/Microfibril/ | + | Once secreted, individual cellulose chains self-assemble to from semi-crystalline cellulose <scene name='82/824000/Microfibril/4'>micro-fibrils</scene>. <scene name='82/824000/Microfibril/2'>Internal cellobiose units</scene> are completely surrounded. 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. |
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Revision as of 14:51, 5 July 2023
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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