Catalytic triads and their relatives

Dodson, Guy; Wlodawer, Alexander

doi:10.1016/s0968-0004(98)01254-7

Cited by 633 publications

(528 citation statements)

References 29 publications

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“…The arrangement of the catalytic triad is as expected, with the serine acting as a nucleophile to attack the carbonyl carbon, and the histidine in position to polarize the serine oxygen and catalyze the removal of the proton from the attacking nucleophile. The aspartic acid is found on the opposite side of the histidine from the serine, as expected for its function of orienting the histidine (51). Note that the catalytic histidine provides the hydrogen for the methanol leaving group of JH (5).…”

Section: Inhibitor Bindingmentioning

confidence: 82%

Structural Studies of a Potent Insect Maturation Inhibitor Bound to the Juvenile Hormone Esterase ofManduca sexta^,

et al. 2006

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Juvenile hormone (JH) is an insect hormone containing an α,β unsaturated ester consisting of a small alcohol and long, hydrophobic acid. JH degradation is required for proper insect development. One pathway of this degradation is through juvenile hormone esterase (JHE), which cleaves the JH ester bond to produce methanol and JH acid. JHE is a member of the functionally divergent α/β-hydrolase family of enzymes, and is a highly efficient enzyme that cleaves JH at very low in vivo concentrations. We present here a 2.7 Å crystal structure of JHE from the tobacco hornworm Manduca sexta (MsJHE) in complex with the transition state analog inhibitor 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP) covalently bound to the active site. This crystal structure, the first JHE structure reported, contains a long, hydrophobic binding pocket with the solvent inaccessible catalytic triad located at the end. The structure explains many of the interactions observed between JHE and its substrates and inhibitors, such as the preference for small alcohol groups and long hydrophobic backbones. The most potent JHE inhibitors identified to date contain a trifluoromethyl ketone (TFK) moiety and have a sulfur atom beta to the ketone. In this study, sulfur-aromatic interactions were observed between the sulfur atom of OTFP and a conserved aromatic residue in the crystal structure. Mutational analysis supported the hypothesis that these interactions contribute to the potency of sulfur-containing TFK inhibitors. Together these results clarify the binding mechanism of JHE inhibitors and provide useful observations for the development of additional enzyme inhibitors for a variety of enzymes. NIH Public Access Author ManuscriptBiochemistry. Author manuscript; available in PMC 2014 December 23. Figure 1A) is a sesquiterpenoid insect hormone that controls a wide range of biological processes. JH and/or its metabolites are known to have effects on insect life cycle processes such as development, metamorphosis, reproduction, diapause, migration, polyphenism and metabolism (1, 2). Perturbation of this system can have deleterious consequences for the insect, a fact which has been exploited for pest control. For example, the JH analog methoprene is a significant chemical line of defense against the larvae of mosquitoes that carry West Nile Virus (3). JH can be metabolized through cleavage of either its epoxide or ester moiety. The relative importance of these two pathways, both catalyzed by α/β-hydrolase enzymes (4-6), varies with insect species, development stage and tissue. Normal lepidopteran metamorphosis, for example, requires the degradation of JH via ester hydrolysis. Inhibition of ester hydrolysis leads to abnormally large larvae and delayed pupation (7). The enzyme responsible for this ester hydrolysis is juvenile hormone esterase (JHE), which is found in the hemolymph and other tissues of insects at key times in development.Insects have significant effects on human health, as vectors for diseases such as malaria and virus induced en...

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Section: Inhibitor Bindingmentioning

confidence: 82%

Structural Studies of a Potent Insect Maturation Inhibitor Bound to the Juvenile Hormone Esterase ofManduca sexta^,

et al. 2006

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“…The deduced amino acid sequence of HlSP showed the highest similarity with the midgut serine proteinase of Rhipicephalus appendiculatus (AAC79567) and also showed similarity with mammalian pancreatic elastases. HlSP has shown to conserve catalytic triad, His-57, Asp-102 and Ser-195 (chymotrypsinogen numbering), which is indispensable for enzyme activity [4] and there are highly conserved regions among mammalian and arthropod serine proteinases. The endogenous enzymes found to be expressed throughout the development of H. longicornis and were localized in the midgut epithelial cells of the ticks [9].…”

Section: Discussionmentioning

confidence: 99%

Enzymatic Characterization of a Cubilin-Related Serine Proteinase from the Hard Tick Haemaphysalis longicornis

et al. 2004

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ABSTRACT. In the present study, we performed enzymatic characterization of Haemaphysalis longicornis serine proteinase (HlSP) with a view to shed light on the mechanisms of blood digestion in the hard ticks. Escherichia coli-expressed recombinant HlSP (rHlSP) was shown to potently hydrolyze the synthetic substrates Bz-(DL)-Arg-pNA, Z-Ala-Ala-Leu-pNA and Suc-Ala-Ala-Ala-pNA and yielded an activity of 31.5, 88.2 and 18.3 µmol/min/mg protein, respectively at an optimum temperature of 25°C. However, the enzyme showed little activity to hydrolyze the substratese Suc-Arg-Pro-Phe-His-Leu-Leu-Val-Tyr-MCA and Pyr-Phe-Leu-pNA. The optimum pH for the enzyme was shown to be 4.0 to 5.0. Several inhibitors such as antipain, leupeptin and phenylmethylsulfonyl fluoride (PMSF), specific for serine proteinase were shown to inhibit enzyme activity by 20-82%, while E-64 (specific for cysteine proteinases) and pepstatinA (specific for aspartic proteinases) had shown only little inhibitory effects on it. This is the first report on enzymatic characterization of a functional serine proteinase from the hard ticks. KEY WORDS: enzyme activity, Haemaphysalis longicornis, serine proteinase.J. Vet. Med. Sci. 66(10): 1195-1198, 2004 Ticks and tick-borne diseases are of extreme importance throughout the world and the associated economic losses are immense. Reliance on acaricides for tick control has led to serious problems which include development of resistance to acaricides that created control problems [5], and increased the threat to the wide-spread occurrence of the pathogens associated with ticks. In addition, chemical residues in animal products, and the effects of such chemicals on the environment, must be considered when new acaricides are developed.Proteolytic enzymes may represent interesting target molecules for drug design because of its involvement in the mediation of a wide range of cellular processes such as protein metabolism and the processing of precursor proteins in the living organisms [11]. In haematophagous ticks, blood digestion in the midgut is thought to be the most essential process because it is the source of energy as well as the most critical interface between the ticks and the pathogens that transmitted by ticks. Studies have reported that aspartic and cysteine proteinases exert proteolytic role, in the midguts [8,13] of the hard tick Boophilus microplus.The hard tick Haemaphysalis longicornis is distributed in a vast area of Eurasia, including Japan [6], where it transmits a wide range of pathogens, including viruses, rickettsia and protozoan parasites, causing important human and animal diseases [17]. In particular, H. longicornis serves as a vector of Theileria orientalis, which is the most economically important protozoan infectious disease of cattle in Asia [6]. In contrast to the extensive reports on proteinase activities in haematophagous insects, very little is known about these activities in the hard tick H. longicornis despite of its high vector potentiality.Recently, we cloned and partially characteri...

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“…The stabilization of existing charges in the transition state results in the exceptional catalytic power of AChE. 43,45,51,[54][55][56][57] This mechanism is represented in Figure 4. His-440 has a high mobility during the catalytic action of AChE, 58 and its exact positioning is fundamental for achieving optimal catalytic activity.…”

Section: Ache Active Sitementioning

confidence: 99%

Organophosphorus compounds as chemical warfare agents: a review

Delfino¹,

Ribeiro²,

Figueroa‐Villar³

2009

J. Braz. Chem. Soc.

231

178

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Os agentes de guerra química constituem uma das maiores ameaças do mundo moderno. Dentre estes, destacam-se os agentes neurotóxicos, em virtude de sua alta letalidade e periculosidade. Eles são compostos organofosforados que atuam pela inibição da enzima acetilcolinesterase, a qual é fundamental no processo de transmissão de impulsos nervosos. Existem várias formas de tratamento para a intoxicação por organofosforados, mas nenhuma delas é eficaz contra todos os agentes conhecidos ou contra todos os seus efeitos. Esta revisão tem como foco o uso de compostos organofosforados como agentes neurotóxicos de guerra química. Após uma breve introdução histórica, será feita uma discussão sobre as principais características estruturais e biológicas da acetilcolinesterase, seguida por uma revisão das propriedades dos compostos organofosforados e da sua aplicação como agentes de guerra química. Por fim, serão discutidas as formas de tratamento contra estes agentes, com ênfase nas oximas usadas para reativar a acetilcolinesterase inibida.Chemical warfare agents constitute one of the greatest threats in the modern world. Among them, the neurotoxic agents are of special interest due to their high lethality and danger. Neurotoxic agents are organophosphorus compounds that act by inhibiting the enzyme acetylcholinesterase, which is fundamental for the control of transmission of nervous impulses. There are several ways of treating intoxication by organophosphorus compounds, but none of them is efficient against all the known neurotoxic agents or against all of their effects. This review focus on the use of organophosphorus compounds as neurotoxic chemical warfare agents. After a brief historical introduction, it will be done a discussion about the structural and biological characteristics of acetylcholinesterase, followed by a review of the properties of organophosphorus compounds and their application as chemical warfare agents. Finally, the ways of treatment against intoxication with these agents will be discussed, with emphasis on the oximes used for reactivating the inhibited acetylcholinesterase.

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Catalytic triads and their relatives

Cited by 633 publications

References 29 publications

Structural Studies of a Potent Insect Maturation Inhibitor Bound to the Juvenile Hormone Esterase ofManduca sexta^,

Structural Studies of a Potent Insect Maturation Inhibitor Bound to the Juvenile Hormone Esterase ofManduca sexta^,

Enzymatic Characterization of a Cubilin-Related Serine Proteinase from the Hard Tick Haemaphysalis longicornis

Organophosphorus compounds as chemical warfare agents: a review

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Catalytic triads and their relatives

Cited by 633 publications

References 29 publications

Structural Studies of a Potent Insect Maturation Inhibitor Bound to the Juvenile Hormone Esterase ofManduca sexta,

Structural Studies of a Potent Insect Maturation Inhibitor Bound to the Juvenile Hormone Esterase ofManduca sexta,

Enzymatic Characterization of a Cubilin-Related Serine Proteinase from the Hard Tick Haemaphysalis longicornis

Organophosphorus compounds as chemical warfare agents: a review

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Structural Studies of a Potent Insect Maturation Inhibitor Bound to the Juvenile Hormone Esterase ofManduca sexta^,

Structural Studies of a Potent Insect Maturation Inhibitor Bound to the Juvenile Hormone Esterase ofManduca sexta^,