Chemoenzymatic synthesis of 1-deaza-pyridoxal 5′-phosphate

Griswold, Wait R.; Toney, Michael D.

doi:10.1016/j.bmcl.2010.01.002

Cited by 9 publications

(15 citation statements)

References 23 publications

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“…21 The BIE for [2,3,3- 2 H]-L-aspartate reacting with K258A/deazaPLP is 1.15 ± 0.04 based on three independent determinations, indicating that, as expected, in AAT the pyridine nitrogen is important to enforcing ground state destabilization. This is additionally supported by the reported BIE of 1.26 for alanine racemase.…”

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confidence: 65%

Ground-State Electronic Destabilization via Hyperconjugation in Aspartate Aminotransferase

et al. 2012

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Binding isotope effects for L-aspartate reacting with the inactive K258A mutant of PLP-dependent aspartate aminotransferase to give a stable external aldimine intermediate are reported. They provide direct evidence for electronic ground state destabilization via hyperconjugation. The smaller equilibrium isotope effect with deazaPLP-reconstituted K258A indicates that the pyridine nitrogen plays an important role in labilizing the Cα-H bond.

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confidence: 65%

Ground-State Electronic Destabilization via Hyperconjugation in Aspartate Aminotransferase

et al. 2012

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“…[67] The coenzyme analogue was used to reconstitute apo-AAT. The internal aldimine as well as the external aldimine enzyme forms were crystallized and their X-ray structures determined (Figure 5).…”

Section: Plp Protonation State and Reaction Specificitymentioning

confidence: 99%

Aspartate aminotransferase: An old dog teaches new tricks

Toney

2014

Archives of Biochemistry and Biophysics

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110

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Aspartate aminotransferase (AAT) is a prototypical pyridoxal 5′-phosphate (PLP) dependent enzyme that catalyzes the reversible interconversion of L-aspartate and α-ketoglutarate with oxalacetate and L-glutamate via a ping-pong catalytic cycle in which the pyridoxamine 5′-phosphate enzyme form is an intermediate. There is a bountiful literature on AAT that spans approximately 60 years, and much fundamental mechanistic information on PLP dependent reactions has been gained from its study. Here, we review our recent work on AAT, where we again used it as a test bed for fundamental concepts in PLP chemistry. First, we discuss the role that coenzyme protonation state plays in controlling reaction specificity, then ground state destabilization via hyperconjugation in the external aldimine intermediate is examined. The third topic is light enhancement of catalysis of Cα-H deprotonation by PLP in solution and in AAT, which occurs through a triplet state of the external aldimine intermediate. Lastly, we consider recent advances in our analyses of enzyme multiple sequence alignments for the purpose of predicting mutations that are required to interconvert structurally similar but catalytically distinct enzymes, and the application of our program JANUS to the conversion of AAT into tyrosine aminotransferase.

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“…[91] We are interested in this coenzyme analogue because it is isosteric with PLP and completely removes the ring nitrogen. No positive charge can develop on the ring and, additionally, the role of the greater electronegativity of N versus C can be deciphered.…”

Section: Plp Protonation Statementioning

confidence: 99%

Controlling reaction specificity in pyridoxal phosphate enzymes

Toney

2011

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

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155

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Pyridoxal 5'-phosphate enzymes are ubiquitous in the nitrogen metabolism of all organisms. They catalyze a wide variety of reactions including racemization, transamination, decarboxylation, elimination, retro-aldol cleavage, Claisen condensation, and others on substrates containing an amino group, most commonly α-amino acids. The wide variety of reactions catalyzed by PLP enzymes is enabled by the ability of the covalent aldimine intermediate formed between substrate and PLP to stabilize carbanionic intermediates at Cα of the substrate. This review attempts to summarize the mechanisms by which reaction specificity can be achieved in PLP enzymes by focusing on three aspects of these reactions: stereoelectronic effects, protonation state of the external aldimine intermediate, and interaction of the carbanionic intermediate with the protein side chains present in the active site.

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Chemoenzymatic synthesis of 1-deaza-pyridoxal 5′-phosphate

Cited by 9 publications

References 23 publications

Ground-State Electronic Destabilization via Hyperconjugation in Aspartate Aminotransferase

Ground-State Electronic Destabilization via Hyperconjugation in Aspartate Aminotransferase

Aspartate aminotransferase: An old dog teaches new tricks

Controlling reaction specificity in pyridoxal phosphate enzymes

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