General Base Catalysis of Ester Hydrolysis<sup>1</sup>

Stefanidis, Dimitrios; Jencks, William P.

doi:10.1021/ja01468a044

Cited by 185 publications

(117 citation statements)

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“…(1984, 1985, 1987a,b), Talesa et al (1988Talesa et al ( , 1989, Uotila (1973Uotila ( , 1979 (Ball & Vander Jagt, 1981). This is in keeping with the nucleophilicity of the imidazole group and the reactivity of N-acylimidazoles towards hydrolysis (Hall et al, 1978;Jencks & Carriuolo, 1959) (Fig. 5).…”

Section: Glyoxalase IIsupporting

confidence: 68%

“…Little is known of its reactivity with proteins, but from the chemical model studies of the thioesters with imidazole (Jencks & Carriuolo, 1959;Hall et al, 1978), it is expected that reactive histidyl residues in proteins proximate to a suitable recognition site for the glutathione moiety will describe and define the locus of S-D-lactoylglutathione biological reactivity. Szent-Gyorgyi (1977) …”

Section: Lactoylglutathionementioning

confidence: 99%

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The glyoxalase system: new developments towards functional characterization of a metabolic pathway fundamental to biological life

Thornalley

1990

Biochemical Journal

716

499

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Section: Glyoxalase IIsupporting

confidence: 68%

Section: Lactoylglutathionementioning

confidence: 99%

The glyoxalase system: new developments towards functional characterization of a metabolic pathway fundamental to biological life

Thornalley

1990

Biochemical Journal

716

499

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“…This magnitude of rate enhancement is similar to that for the hydrolysis of aspartyl peptide 1-esters (14). However, acetylimidazole (an alternative model for the glutamyl activation) is hydrolyzed without anchimeric assistance at a rate similar to that for the a2M active site (15). Thus, we are unable to distinguish between a thiolester and an alternative activation mechanism with a buried thiol.…”

Section: Methodsmentioning

confidence: 49%

Reactive site in human alpha 2-macroglobulin: circumstantial evidence for a thiolester.

Howard¹

1981

Proc. Natl. Acad. Sci. U.S.A.

128

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The reaction ofmethylamine with a2-macroglobulin (a2M) and iodo[2-3H]acetic acid, a tryptic peptide was isolated that contained both labels in the same ratio as in the original protein. From the chymotryptic digest of the tryptic peptide, a single radiolabeled peptide was isolated. The amino acid sequence of the chymotryptic peptide was the same as that previously reported to include y-glutamylmethylamide. This is circumstantial evidence for a thiolester between the cysteine and a glutamic acid located three residues away in the primary sequence. A reaction mechanism involving a pyroglutamyl intermediate derived from the thiolester is suggested to explain the autolysis. Kinetic analysis of the autolysis reaction is consistent with this intermediate and mechanism.The human plasma proteins a2-macroglobulin (a2M), complement component C-3, and complement component C-4 have a unique reactivity with nucleophiles, a property that can lead to complete inactivation of the protein (1-5). We have shown that, when methylamine is incubated with one ofthese proteins, a specific glutamic residue is irreversibly and covalently modified as y-glutamylmethylamide (1-3, 5). For a2M, the amino acid sequence ofa 56-residue glycopeptide containing the modified residue has been reported (2).A second property common to these proteins is the lability of a single peptide bond in the partially denatured protein (3,(5)(6)(7)(8)(9). Upon incubation of the protein at 80°C in buffer alone, or at lower temperatures in denaturing buffers, the protein is specifically fragmented-e.g., the a2M subunit (Mr 185,000) is cleaved into peptides ofMr 115,000 and 65,000 (fragments I and II), the a-subunit of C-3 is cleaved into peptides of Mr 80,000 and 55,000, and the a-subunit of C-4 is cleaved into peptides of Mr 60,000 and 45,000. The denaturation-dependent peptide bond hydrolysis can be prevented by prior reaction of the protein with nucleophiles. For C-3 and C-4, which are composed ofmore than one type ofsubunit, the methylamine-reactive site and the peptide-hydrolysis site are in the same subunit (3, 5). Recently, we (8) reported for a2M that the site offragmentation is the peptide bond on the amino-terminal side of the reactive glutamic residue. The cleavage proceeds with the concerted formation ofan amino-terminal pyroglutamic acid for the newly formed peptide fragment, fragment II (the carboxyl-terminal third of the original a2M subunit). Because nucleophilic substitution and peptide bond scission occur at the same glutamic residue in a2M, we (2, 8) have concluded that both phenomena are the consequence of a single highly activated residue. The similarity of both reactions in a2M, C-3, and C-4 led us (1,2,8) to suggest that the active sites in three proteins should have sequence homology and a common mechanism of activation. The sequence homology in the active site of a2M (1, 2) and C-3 (4) has been confirmed.Although we (1-3) have hypothesized that the carboxyl group could be activated by either an oxyester or a thiolester, the nature...

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“…This amazed me because nucleophilic attack of imidazole on acetylimidazole can only give acetylimidazole. After doing some reading, I learned that I had rediscovered general base catalysis-the imidazole abstracts a proton from water as it attacks the acetylimidazole, making H 2 O a stronger base and a more effective nucleophile, as shown in Figure 2 (9).…”

Section: Back To Chemistrymentioning

confidence: 99%

From Chemistry to Biochemistry to Catalysis to Movement

Jencks

1997

Annu. Rev. Biochem.

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Mechanisms of chemical reactions can often be predicted by determining the dependence of the lifetime of reaction intermediates on the structure of the reactants. When there is no lifetime in the presence of another reactant or catalyst the reaction proceeds through an enforced concerted mechanism.Noncovalent binding interactions between enzymes and their substrates provide a major contribution to catalysis by decreasing entropy and by destabilizing the ground state relative to the transition state, as well as by covalent and noncovalent chemical interactions with the substrate.Movement in biological systems, such as muscle contraction and the active transport of ions, is generally brought about through a series of alternating chemical and vectorial steps that involve a series of changes in the specificity for catalysis of the chemical and vectorial reactions. These changes divide the overall reaction into segments so that neither the chemical nor the vectorial reaction will be completed unless the other is also completed. CONTENTS

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General Base Catalysis of Ester Hydrolysis¹

Cited by 185 publications

References 0 publications

The glyoxalase system: new developments towards functional characterization of a metabolic pathway fundamental to biological life

The glyoxalase system: new developments towards functional characterization of a metabolic pathway fundamental to biological life

Reactive site in human alpha 2-macroglobulin: circumstantial evidence for a thiolester.

From Chemistry to Biochemistry to Catalysis to Movement

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General Base Catalysis of Ester Hydrolysis1

Cited by 185 publications

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The glyoxalase system: new developments towards functional characterization of a metabolic pathway fundamental to biological life

The glyoxalase system: new developments towards functional characterization of a metabolic pathway fundamental to biological life

Reactive site in human alpha 2-macroglobulin: circumstantial evidence for a thiolester.

From Chemistry to Biochemistry to Catalysis to Movement

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General Base Catalysis of Ester Hydrolysis¹