Earlier investigations have shown that the irreversible inhibition of delta -chymotrypsin with the axially substituted trans-3-(2,4-dinitrophenoxy)-2,4-dioxa-3 lambda (5)-phosphabicyclo[4.4.0]decan-3-one (=2-(2,4-dinitrophenoxy)hexahydro-4H-1,3,2-benzodioxaphosphorin 2-oxide) proceeds under inversion of the configuration at the P-atom, Since this assignment is based on the comparison of the respective chemical shifts with model compounds, the covalent nature of the binding interaction between enzyme and inhibitor was formulated in analogy. To prove this assumption, inhibition experiments were performed with the deutereted inhibitor (+/-)-trans-3-(2,4-dinitrophenoxy)-2,4-dioxa-3 lambda (5)-phospha(1,5,5-H-2(3))bicyclo[4.4.0]decan-3-one ((+/-)-6a). P-31H-2}-NMR-Spectroscopic monitoring of the reaction of stoichiometric amounts of the enzyme with (+/-)-6a at pH 7.8 yielded the diastereoisomeric adducts 9 (-3.88 ppm) and 9' (-3.96 ppm). Comparing the P-31 chemical shifts of the corresponding deuterated covalent phosphoserine model compounds 8a/8a' (-6.70 ppm, axial) and 8b/8b' (-4.11/-4.13 ppm, equatorial) confirmed the inversion of the configuration at the P-atom. H-1-Correlated P-31H-2}-NMR spectra revealed a cross peak of the Ser(195)-H-2 (4.35 ppm) with the P-atom of the inhibitor at -3.88/-3.96 ppm, thus establishing the covalent nature of the Ser(195)-O-P bond.
Synthesis of Enantiomerically Pure 1,5,5-Trideuteratedcis- andtrans-2,4-Dioxa-3-phosphadecalins.31P-NMR Evidence of Covalent-Bond Formation and the Stereochemical Implications in the Course of the Inhibition ofδ-Chymotrypsin
作者:Markus J. Stöckli、Peter Rüedi
DOI:10.1002/hlca.200790215
日期:2007.11
The irreversible inhibition of δ-chymotrypsin with the enantiomericallypure, P(3)-axially and P(3)-equatorially X-substituted cis- and trans-configurated 2,4-dioxa-3-phospha(1,5,5-2H3)bicyclo[4.4.0]decane 3-oxides (X=F, 2,4-dinitrophenoxy) was monitored by 31P-NMR spectroscopy. 1H-Correlated 31P2H}-NMR spectra enabled the direct observation of the vicinal coupling (3J) between the P-atom of the inhibitor
δ-胰凝乳蛋白酶的对映体纯,P(3)轴向和P(3)-赤道X取代的顺式和反式配置的2,4-dioxa-3-phospha(1,5,5- )的不可逆抑制通过31 P-NMR光谱监测2 H 3)双环[4.4.0]癸烷3-氧化物(X = F,2,4-二硝基苯氧基)。1个H-相关31 p 2 H} -NMR光谱使邻位耦合的直接观察(3 Ĵ抑制剂的P-原子和CH之间)2的Ser O部分195(= '序列195 '(C高2O)),从而在受抑制的酶中建立了'Ser 195 '(CH 2 OP)键的共价性质。磷酸化的立体化学过程取决于抑制剂的结构,并且发现在P原子上纯净的反转,反转和保留以及构型的净保留。