'''PSEUDOMONAS LIPASE COMPLEXED WITH RC-(RP, SP)-1,2-DIOCTYLCARBAMOYLGLYCERO-3-O-OCTYLPHOSPHONATE'''
===PSEUDOMONAS LIPASE COMPLEXED WITH RC-(RP, SP)-1,2-DIOCTYLCARBAMOYLGLYCERO-3-O-OCTYLPHOSPHONATE===
==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.
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{{ABSTRACT_PUBMED_9660188}}
==About this Structure==
==About this Structure==
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[[Category: Pseudomonadaceae]]
[[Category: Pseudomonadaceae]]
[[Category: Triglyceride analogue]]
[[Category: Triglyceride analogue]]
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Revision as of 14:05, 3 July 2008
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Structural basis of the chiral selectivity of Pseudomonas cepacia lipase., Lang DA, Mannesse ML, de Haas GH, Verheij HM, Dijkstra BW, Eur J Biochem. 1998 Jun 1;254(2):333-40. PMID:9660188
