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| {{STRUCTURE_4lip| PDB=4lip | SCENE= }} | | {{STRUCTURE_4lip| PDB=4lip | SCENE= }} |
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| '''PSEUDOMONAS LIPASE COMPLEXED WITH RC-(RP, SP)-DIBUTYLCARBAMOYLGLYCERO-3-O-BUTYLPHOSPHONATE'''
| | ===PSEUDOMONAS LIPASE COMPLEXED WITH RC-(RP, SP)-DIBUTYLCARBAMOYLGLYCERO-3-O-BUTYLPHOSPHONATE=== |
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| ==Overview==
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| To investigate the enantioselectivity of Pseudomonas cepacia lipase, inhibition studies were performed with Sc- and Rc-(Rp,Sp)-1,2-dialkylcarbamoylglycero-3-O-p-nitrophenyl alkylphosphonates of different alkyl chain lengths. P. cepacia lipase was most rapidly inactivated by Rc-(Rp,Sp)-1,2-dioctylcarbamoylglycero-3-O-p-nitrophenyl octylphosphonate (Rc-trioctyl) with an inactivation half-time of 75 min, while that for the Sc-(Rp,Sp)-1,2-dioctylcarbamoylglycero-3-O-p-nitrophenyl octyl-phosphonate (Sc-trioctyl) compound was 530 min. X-ray structures were obtained of P. cepacia lipase after reaction with Rc-trioctyl to 0.29-nm resolution at pH 4 and covalently modified with Rc-(Rp,Sp)-1,2-dibutylcarbamoylglycero-3-O-p-nitrophenyl butyl-phosphonate (Rc-tributyl) to 0.175-nm resolution at pH 8.5. The three-dimensional structures reveal that both triacylglycerol analogues had reacted with the active-site Ser87, forming a covalent complex. The bound phosphorus atom shows the same chirality (Sp) in both complexes despite the use of a racemic (Rp,Sp) mixture at the phosphorus atom of the triacylglycerol analogues. In the structure of Rc-tributyl-complexed P. cepacia lipase, the diacylglycerol moiety has been lost due to an aging reaction, and only the butyl phosphonate remains visible in the electron density. In the Rc-trioctyl complex the complete inhibitor is clearly defined; it adopts a bent tuning fork conformation. Unambiguously, four binding pockets for the triacylglycerol could be detected: an oxyanion hole and three pockets which accommodate the sn-1, sn-2, and sn-3 fatty acid chains. Van der Waals' interactions are the main forces that keep the radyl groups of the triacylglycerol analogue in position and, in addition, a hydrogen bond to the carbonyl oxygen of the sn-2 chain contributes to fixing the position of the inhibitor.
| | The line below this paragraph, {{ABSTRACT_PUBMED_9660188}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 9660188 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_9660188}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Pseudomonadaceae]] | | [[Category: Pseudomonadaceae]] |
| [[Category: Triglyceride analogue]] | | [[Category: Triglyceride analogue]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 22:26:14 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jul 3 13:43:00 2008'' |
