Acceleration of a Phosphate Diester Transesterification Reaction by Bis(alkylguanidinium) Receptors Containing an Appended General Base

Abstract

There is considerable interest in designing synthetic catalysts that can hydrolyze phosphate diesters" -3 1 since such artificial nucleases have potential applications as novel antiviral and anticancer therapeutic agent^.[^-^] An important strategy for developing artificial enzymes is to incorporate, into a synthetic framework. functional groups known to be present in the enzyme's active site and that are essential for maintaining catalytic activity. The DNA and RNA hydrolyzing enzyme, staphylococcal nuclease (SN), contains two key arginine residues, Arg35 and Arg87, in its active site."] Site directed mutagenesis studies have establishedr8-101 that only one arginine residue (Arg35) binds to the monoanionic substrate, but both residues are required for phosphate ester hydrolysis. In an attempt to exploit this important feature of SN, weI1'l and othersr1'-'*] have designed mono-and bis(guanidinium) derivatives that bind with phosphate diesters in organic solvents. We have shown that certain bis(guanidinium) receptors can mimic SN and accelerate the transesterification of phosphate diesters. A key requirement for these guanidinium receptors[1y1 and related systemsL2, 2 0 , ''I is the addition of a general base (e.g. lutidine, tetramethylguanidine. imidazole) to deprotonate the hydroxyl nucleophile (Scheme 1 , A). In an attempt to design a receptor that contains H 0 H 02" \ Scheme 1 . Transesterification of HPNPP mediated by bis(guanidinium) receptors and an added base (A) and by a bis(guanid1nium) receptor with an appended basic group ( B i .all the necessary components for catalysis, we have linked general base groups to the bis(guanidinium) receptors. The receptor design is based on bis(a1kylguanidinium) derivatives that remain protonated in the presence of a wide range of basic groups. These receptors can potentially accelerate phosphate ester cleavage by providing a hydrogen-bonding cleft to increase the electrophilicity and facilitate nucleophilic attack on phosphorus upon binding in the manner depicted in Scheme 1, B. In this paper we report a series of alkylguanidinium ions 1-5 containing appended nitrogen bases and compare their efficiencies in accelerating the transesterification reaction of the RNA model, 2-hydroxypropyl-para-nitrophenylphosphate (HPNPP) .[22s 231 ) Telefdx. Int. code +(41?) 624-8552 [**I This work was supported by the U.S. Office of Naval Research. A n p i C'iwm. Inr. Ed. Engl. 1995, 34. N o . I 1 :<) VCH Verlugsgesrllscliu/,/r mhH, D-6Y45I Weinhein!, 1995 0570-0833iYSillll-/237 S I(J.(JO+ . 3 ; 0 C? VCH V e r l a~s~a s e l l s~~l i u~t mhH, D-69451 Wrinhrim 1995 0570-083S~9S~iiIi-1~3X S 1 O . O O i .25/0 Angeu'. Chem. In[. Ed. EngI. 1995, 34. No. I ! of HPNPP [ZY]. The rate constants were obtained by fitting at least three half-lives of the reaction according to a first-order kinetics equation. For slower reactions. rate conslants were calculated from the initial rates. First-order rate constants were calculated from the slopes of the linear plots of absorbance versus time by convertin...

Hydrolytical Cleavage of TAR‐RNA, the trans‐Activation Responsive Region of HIV‐1, by a Bis(guanidinium) Catalyst Attached to Arginine

“…2): in dipolar aprotic solvents nucleophilic substitutions of a model phosphodiester are accelerated by factors up to 4800 [62] [63]. Similar results have been obtained by other scientists [59] [64] [65]. With RNA substrates, 3 is supposed to facilitate the intramolecular nucleophilic attack of 2'-OH at P-atom, leading to strand cleavage and the formation of 2',3'-cyclic phosphates.…”

Phosphate-Affinity Gel Electrophoresis Using a Phos-Tag Molecule for Phosphoproteome Study

“…The majority of the hosts are organic molecules bearing acidic hydrogen atoms at complementary positions to the formation of hydrogen bonds with phosphate anions. The dissociation constants (K d = [host][phosphate]/[phosphate-bound host]) are in the range of 10 -2 to 10 -6 M in non-aqueous solvents such as chloroform and dimethyl sulfoxide (Ariga and Anslyn, 1992;Jubian et al, 1995;Berger and Schmidtchen, 1996;Magrans et al, 1996). These hydrogen bonds, however, cannot compete against the hydration of phosphate anions in water, resulting in the dissociation of the phosphate-bound host complexes.…”

Design of artificial nucleases and studies of their interaction with DNA

“…Besides, Hamilton et al [15] . investigated the cleavage behavior of 2-hydroxypropyl 4-nitrophenyl phosphate (HPNPP, RNA mimic) promoted by bis (guanidinium) compound 2.…”