Sandbox Reserved 711: Difference between revisions
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[[Image:proposed mechanism.png | 332 px |center|thumb|'''Proposed mechanism for family 28 of glycoside hydrolases''']] | [[Image:proposed mechanism.png | 332 px |center|thumb|'''Proposed mechanism for family 28 of glycoside hydrolases''']] | ||
== Description of the structure == | == Description of the structure == | ||
<Structure load='1czf' size='400' frame='true' align='right' caption='Insert caption here' scene='Insert optional scene name here' /> | |||
The endopolygalacturonase II from Aspergillus niger has a beta-helix structure<ref>http://www.ncbi.nlm.nih.gov/pubmed/10521427</ref>: the chain folds into 10 turns, shaping the faces of a right-handed helix consisting in 4 parallel beta-sheets - PB1, PB2a, PB2b and PB3 - separated by loops. The helix is closed at its N-terminal end by a small alpha-helix. | The endopolygalacturonase II from Aspergillus niger has a beta-helix structure<ref>http://www.ncbi.nlm.nih.gov/pubmed/10521427</ref>: the chain folds into 10 turns, shaping the faces of a right-handed helix consisting in 4 parallel beta-sheets - PB1, PB2a, PB2b and PB3 - separated by loops. The helix is closed at its N-terminal end by a small alpha-helix. | ||
4 disulfide bridges, conserved in all endopolygalacturonases of ''A. Niger'', hold together different parts of the chain, and particularily one of these attaches the N-terminal helix to the PB2b sheet. | 4 disulfide bridges, conserved in all endopolygalacturonases of ''A. Niger'', hold together different parts of the chain, and particularily one of these attaches the N-terminal helix to the PB2b sheet. | ||
The loops separating PB1 and PB2a are longer on the C-terminal end, and those between PB3 and PB1 on the N-terminal end, what forms a cleft between two extensions outside of the the beta-helix. Its shape, open at both ends of the protein, allows the fixation of a linear glucidic chain, and is suited to the endohydrolytic mode of action. This cleft is a higly conserved region. | The loops separating PB1 and PB2a are longer on the C-terminal end, and those between PB3 and PB1 on the N-terminal end, what forms a cleft between two extensions outside of the the beta-helix. Its shape, open at both ends of the protein, allows the fixation of a linear glucidic chain, and is suited to the endohydrolytic mode of action. This cleft is a higly conserved region. | ||
