Enzymes phosphonate analogues

Additional information <1, 7-9, 12-17, 21> (<7> inhibitory effect of phosphonate analogues of 1,3-diphosphoglycerate, overview [49] <21> no effect by glucose 6-phosphate, fructose 6-phosphate, fructose 1,6-phosphate, pyruvate, phosphoenolpyruvate and lactate [70] <13> double-inhibition studies, kinetics, modeling of inhibitor binding, e.g. phosphate [55] <13> enzyme is regulated by multivalent anions, overview [55] <8> no inhibition by Hg [25] <1,7,9,12-17> yeast enzyme is insensitive to thiol reagents [17]) [17, 25, 49, 55, 70]... 

The requirement of the remaining enzymes, KD0-8-phosphate synthase, KD0-8-phosphate phosphatase and CMP-KDO synthetase, for their natural substrates, D-arabinose-5-phosphate + PEP, KD0-8-phosphate and KDO + CTP, respectively, was specific and the inhibition studies with substrate analogues were disappointing. Of the compounds tested as potential substrates of KD0-8-phosphate synthase, only the isosteric phosphonate analogue (Compound 11, Table III) of D-arabinose-5-phosphate was an alternate substrate (see Ref. 28). There were a number of weak competitive inhibitors of the synthase reaction (Compounds 2, 5, 6, 7, 15,and 19,Table III) the best inhibitor of the synthase reaction was 2-deoxy-2-fluoro-D-arabinonate-5-phosphate (compound 14, Table III). 

The first enzyme which is specific for aromatic amino acid biosynthesis is 3-deoxy-D-arabino-heptulosonic 7-phosphate (DAHP) synthase (EC 4.1.2.1.5), which utilizes D-erythrose 4-phosphate (E4P) and phosphoenolpyruvate (PEP) as substrates (Fig. 2). Le Mar chal al.prepared the isosteric homophosphonate of E4P, in which the C-O-P group is replaced by the C-CH2-P group as well as the non-isosteric phosphonate analogue, in which the C-O-P group is replaced by the C-P group (Fig. 3). Both analogues served as substrates for the tyrosine-sensitive DAHP synthase of Escherichia coli, with Vmax values in the ratio 20 3.5 1 for E-4-P, the phosphonate, and the homophosphonate. 

Enzyme properties of phosphonic analogues of D-erythrose 4-phosphate. Biochem. Biophys. Res. Commun. 92 1097-1103. 

The N-methylimido analogue (135) of ADP has been synthesized, and it could be converted enzymically to the triphosphate analogue. The pj-methylimidO triphosphate was also rnade. Blackburn s group have described the synthesis of the Pl, P -dithioderivative (136) of diadenosyl tetraphosphate (ApaA), and some phosphonate analogues (137), 192 and also phosphonate and thiophosphate analogues of ApsA.193... 

Kluger R, Pike DC (1977) Active site generated analogues of reactive intermediates in enzymic reactions. Potent inhibition of pyruvate dehydrogenase by a phosphonate analogue of pyruvate. J Am (Them Soc 99 4504—4506... 

An example of esterase behaviour is provided by a catalytic antibody developed by Tramontano et al. (1988), using a phosphonate transition state analogue [53] as the hapten. The antibody cleaves the carboxylic ester [54, R = Me] with enzyme-like efficiency (kc/ku = 6.25 X 106 = 1.5 mM ... 

Cidofovir (Vistide) is an acyclic phosphonate cytosine analogue with activity against herpesviruses including CMV, HSV-1, HSV-2, EBV, and VZV. It also inhibits adenoviruses, papillomaviruses, polyomaviruses, and poxviruses. Activation of cidofovir requires metabolism to a diphosphate by host cellular enzymes. Because this activation does not depend upon viral enzymes, similar levels of cidofovir diphosphate are seen in infected and uninfected cells. Cidofovir diphosphate competes with deoxycytidine triphosphate (dCTP) for access to viral... 

S.G. Withers, i.P. Street, M.D. Percivai, Fiuorinated carbohydrates as probes of enzyme specificity and mechanism, ACS Symposium Series 374 (1988) 59-77. W.G. Stirtan, S.G. Withers, Phosphonate and aipha-fluorophosphonate analogue probes of the ionization state of pyridoxai 5 -phosphate (PLP) in glycogen phosphor-ylase. Biochemistry 35 (1996) 15057-15064. 

Saccharidic Difluorophosphonates Difluoromethylene phospho-nates have been the focus of numerous works. Indeed, these compounds are able to mimic the phosphate bond in the synthesis of enzyme inhibitors. This interest is obvious for the furanose series in this case, they are non scissible analogues of 5-phosphate nucleosides (cf. Chapter 7). Difluoromethylene phosphonates can be prepared via a radical path starting from compounds that have the difluoromethylene moiety in the pseudo-anomeric position. Nevertheless, methods based on metal derivatives of difluorophosphonates are generally easier and broadly applicable. 

Fig. 4. The use of arsonomethyl phosphonate as an analogue of diphosphate by RNA polymerase. The enzyme accepts the analogue in the reverse of polymerase action. Since the product hydrolyzes, the overall effect is that of an exonuclease, producing nucleoside 5 -phosphates (59).

Phosphonates have been widely used as analogues of carboxylic acids. They have been particularly effective as analogues of tetrahedral transition states that occur in the course of enzyme-catalyzed reactions such as hydrolysis of the amide (peptide) bond. As such, they may be used as inhibitors of enzymes (e.g., 82, 83) or as haptens for producing antibodies that are catalytic (e.g., 84). A notable example is H203P— CH2—CH2—CH(—NH2)—COOH, which has effects that are likely to be due to its interference with glutamate as a neurotransmitter (85). 

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