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| {{STRUCTURE_2oqd| PDB=2oqd | SCENE= }} | | {{STRUCTURE_2oqd| PDB=2oqd | SCENE= }} |
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| '''Crystal Structure of BthTX-II'''
| | ===Crystal Structure of BthTX-II=== |
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| ==Overview==
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| A myotoxic Asp49-phospholipase A(2) (Asp49-PLA(2)) with low catalytic activity (BthTX-II from Bothrops jararacussu venom) was crystallized and the molecular-replacement solution has been obtained with a dimer in the asymmetric unit. The quaternary structure of BthTX-II resembles the myotoxic Asp49-PLA(2) PrTX-III (piratoxin III from B. pirajai venom) and all non-catalytic and myotoxic dimeric Lys49-PLA(2)s. Despite of this, BthTX-II is different from the highly catalytic and non-myotoxic BthA-I (acidic PLA(2) from B. jararacussu) and other Asp49-PLA(2)s. BthTX-II structure showed a severe distortion of calcium-binding loop leading to displacement of the C-terminal region. Tyr28 side chain, present in this region, is in an opposite position in relation to the same residue in the catalytic activity Asp49-PLA(2)s, making a hydrogen bond with the atom Odelta2 of the catalytically active Asp49, which should coordinate the calcium. This high distortion may also be confirmed by the inability of BthTX-II to bind Na(+) ions at the Ca(2+)-binding loop, despite of the crystallization to have occurred in the presence of this ion. In contrast, other Asp49-PLA(2)s which are able to bind Ca(2+) ions are also able to bind Na(+) ions at this loop. The comparison with other catalytic, non-catalytic and inhibited PLA(2)s indicates that the BthTX-II is not able to bind calcium ions; consequently, we suggest that its low catalytic function is based on an alternative way compared with other PLA(2)s.
| | The line below this paragraph, {{ABSTRACT_PUBMED_18261474}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 18261474 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_18261474}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Bthtx-ii]] | | [[Category: Bthtx-ii]] |
| [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 11:27:09 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 04:02:31 2008'' |