Publications and Patents

Most Recent Listed First

Biocatalytic and Regioselective Exchange of 2-O-Benzoyl for 2-O-(m-Substituted)Benzoyl Groups to Make Precursors of Next-Generation Paclitaxel Drugs
Al-Hilfi, A.; Li, Z.; Merz, K.M.; Nawarathne, I.N.; Walker, K.D. ChemCatChem 2024, accepted.
PATENT: Biocatalytic coupling reactions toward regioisomerically enriched alkyl pyrazines
Mao, G.; Attanayake, G.; Walker, K.D. Filed, 13 July 2022, International Application No. PCT/US2022/073705, Patent Number: WO2023288257A2; Publication Date: 19 January 2023. Assignee: Conagen, Inc., Board of Trustees of Michigan State University.

Abstract: The disclosure provides methods of producing substituted pyrazines. The methods comprise, in some embodiments, incubating a certain α-keto-acid, a certain aldehyde, and a pyruvate decarboxylase to form a certain α-hydroxyketone. The methods may further comprise incubating the certain α-hydroxyketone with a certain amine to form a certain substituted dihydropyrazine. The methods may further comprise incubating the certain substituted dihydropyrazine, a base, and an oxidant to form a certain substituted pyrazine. The substituted pyrazines produced by the methods may be regioselectively enriched.

Redirecting tropane alkaloid metabolism reveals pyrrolidine alkaloid diversity in Atropa belladonna
Parks, H.M.; Cinellia, M.A.; Bedewitz, M.A.; Grabarb, J.M.; Hurney, S.M.: Walker, K.D.; Jones, A.D.; Barry C.S. New Phytol. 2023, 237, 1810-1825.
Assessing alkyl methoxypyrazines as predictors of the potato taste defect in coffee
Shingiro, J.B.; Shee, P.K.; Beaudry, R.M.; Thiagarajan, D.; Bourquin, L.D.; Walker, K.D. ACS Food Sci. Technol. 2022, 1738-1745.
Biocatalysis of precursors to new-generation SB-T-taxanes effective against paclitaxel-resistant cancer cells
Al-Hilfi, A.; Walker, K.D. Arch. Biochem. Biophys. 2022, 719, 109165.
A semibiocatalytic approach toward regioisomerically enriched ethyl dimethylpyrazines important in flavor industries
Attanayake, G.; Mao, G.; Walker, K.D. J. Agric. Food Chem. (ACS) 2021, 69, 15314–15324.
Intermolecular amine transfer to enantioenriched trans-3-phenylglycidates by an α/β-aminomutase to access both anti-phenylserine isomers
Shee, P.K.; Yan, H.; Walker, K.D. ACS Catal. 2020, 10, 15071-15082.

CoA Recycling by a benzoate coenzyme A ligase in cascade reactions with aroyltransferases to biocatalyze paclitaxel analogs
Sullivan, S.A.; Nawarathne, I.; Walker, K. D. Arch. Biochem. Biophys. 2020, 683, 108276.

Exploring the scope of an α/β-aminomutase for the amination of cinnamate epoxides to arylserines and arylisoserines
Shee, P.K.; Ratnayake, N.D.; Walter, T.; Goethe, O.; Onyeozili, E.N.; Walker, K. D. ACS Catal. 2019, 9, 7418-7430.

Understanding which residues of the active site and loop structure of a tyrosine aminomutase define its mutase and lyase activities
Attanayake, G.; Walter, T.; Walker, K.D. Biochemistry (ACS) 201857(25), 3503-3514.
in Special Issue: Current Topics in Mechanistic Enzymology
Biocatalysis of a paclitaxel analogue: Conversion of baccatin III to N-debenzoyl-N-(2-furoyl)paclitaxel and characterization of an amino phenylpropanoyl CoA transferase
Thornburg, C. K.; Walter, T.; Walker, K. D. Biochemistry (ACS) 201756(44), 5920–5930.

PATENT: Biosynthesis of Paclitaxel Intermediate
Kevin Walker, Patent No. US 9732365 B2 (US20150284751WO2013191678A1), Aug 15, 2017, Asignee: Michigan State University

Paclitaxel biosynthesis: Adenylation and thiolation domains of an NRPS TycA PheAT module produce various arylisoserine CoA thioesters
Muchiri, R.; Walker, K. D. Biochemistry (ACS) 201756(10), 1415–1425.

Identification and characterization of the missing phosphatase on the riboflavin biosynthesis pathway in Arabidopsis thaliana
(Featured Article, Cover Art)
Sa, N.; Rawat, R.; Thornburg, C.; Walker, K. D.; Roje, S. Plant J. 2016, 88(5), 705–716.

A tyrosine aminomutase from rice (Oryza sativa) isomerizes (S)-α- to (R)-β-tyrosine with unique high enantioselectivity and retention of configuration
Walter, T.; King, Z.; Walker, K. D. Biochemistry (ACS) 201655(1), 1-4.

Layer-by-layer deposition with polymers containing nitrilotriacetate: A convenient route to fabricate metal- and protein-binding films
Wijeratne, S.; Liu, W.; Dong, J.; Ning, W.; Ratnayake, N. D.; Walker, K. D.; Bruening, M. L. ACS Appl. Mater. Interfaces, 2016, 8(16), 10164-10173.

Mutation of aryl binding pocket residues results in an unexpected activity switch in an Oryza sativa tyrosine aminomutase
Walter, T.; Wijewardena, D.; Walker, K. D. Biochemistry (ACS) 2016, 55(25), 3497-3503

Whole-cell biocatalytic production of variously substituted β-aryl- and β-heteroaryl-β-amino acids
Ratnayake, N. D.; Theisen, C.; Walter, T.; Walker, K. D. J. Biotechnol2016, 217, 12-21.

PATENT: Biosynthesis of Paclitaxel Intermediate
Kevin Walker, Patent No. US 20150284751 A1, 2015, Michigan State University

Kinetically and Crystallographically Guided Mutations of a Benzoate CoA Ligase (BadA) Elucidate Mechanism and Expand Substrate Permissivity.
Thornburg, C.K.; Wortas-Strom, S.; Nosrati, M.; Geiger, J.H.; Walker, K.D. 2015 Biochemistry (ACS) 50(40), 6230–6242.

Genome sequencing and analysis of the paclitaxel-producing endophytic fungus Penicillium aurantiogriseum NRRL 62431
Yang, Y.; Zhao, H.; Barrero, R. A.; Zhang, B.; Sun, G.; Wilson, I. W.; Xie, F.; Walker, K. D.; Parks, J. W.; Bruce, R.; Guo, G.; Chen, L.; Zhang, Y.; Huang, X.; Tang, Q.; Liu, H.; Bellgard, M. I.; Qiu, D.; Lai, J.; Hoffman, A. BMC Genomics 2014, 15, 69.

Ring-substituted α-arylalanines for probing substituent effects on the isomerization reaction catalyzed by an aminomutase
Ratnayake, N. D.; Liu, N.; Kuhn, L. A.; Walker, K. D. ACS Catalysis 2014, 4, 3077-3090.

A bacterial tyrosine aminomutase proceeds through retention or inversion of stereochemistry to catalyze its isomerization reaction
Wanninayake, U.; Walker, K. D. J. Am. Chem. Soc. 2013, 135, 11193-11194.
Assessing the deamination rate of a covalent aminomutase adduct by burst phase analysis
Wanninayake, U.; Walker, K. D. Biochemistry (ACS) 2012, 51, 5226-5228.

Insights into the mechanistic pathway of the Pantoea agglomerans phenylalanine aminomutase
Strom, S.; Wanninayake, U.; Ratnayake, N. D.; Walker, K. D.; Geiger, J. H. Angew. Chem. Int. Ed. 2012, 51, 2898-2902.

Taxol biosynthesis: tyrocidine synthetase A catalyzes the production of phenylisoserinyl CoA and other amino phenylpropanoyl thioesters
Muchiri, R.; Walker, K. D. Chem. Biol. 2012, 19, 679-685.

(S)-Styryl-α-alanine used to probe the intermolecular mechanism of an intramolecular MIO-aminomutase
Wanninayake, U.; Deporre, Y.; Ondari, M.; Walker, K. D. Biochemistry (ACS) 2011, 50, 10082-10090.

Mechanistic, mutational, and structural evaluation of a Taxus phenylalanine aminomutase
Feng, L.; Wanninayake, U.; Strom, S.; Geiger, J.; Walker, K. D. Biochemistry (ACS) 2011, 50, 2919-2930.

Stereochemistry and mechanism of a microbial phenylalanine aminomutase
Ratnayake, N. D.; Wanninayake, U.; Geiger, J. H.; Walker, K. D. J. Am. Chem. Soc. 2011, 133, 8531.

Point mutations (Q19P and N23K) increase the operational solubility of a 2α-O-benzoyltransferase that conveys various acyl groups from CoA to a taxane acceptor
Nawarathne, I. N.; Walker, K. D. J. Nat. Prod. 2010, 73, 151.

PATENT: Process for the preparation of (R)-β-arylalanines by coupled racemase/ aminomutase catalysis
Walker, K. D.; Cox, B. M. U.S. Pat. Appl. Publ. 2010, US 20100285540 A1 20101111

Separation of α- from β-arylalanines by nickel nitrilotriacetate chromatography
Wijeratne, S.; Byrne, N. A.; Walker, K. D. J. Sep. Sci. 2010, 33, 1279.

An N-aroyltransferase of the BAHD superfamily has broad aroyl CoA specificity in vitro with analogues of N-dearoylpaclitaxel
Nevarez, D. M.; Mengistu, Y. A.; Nawarathne, I. N.; Walker, K. D. J. Am. Chem. Soc. 2009, 131, 5994.

Enhanced conversion of racemic α-arylalanines to (R)-β-arylalanines by coupled racemase/aminomutase catalysis
Cox, B. M.; Bilsborrow, J. B.; Walker, K. D. J. Org. Chem. 2009, 74, 6953.

Synthesis of 4-deacetyl-1-dimethylsilyl-7-triethylsilylbaccatin III
Ondari, M. E.; Walker, K. D. J. Org. Chem. 2009, 74, 2186.

The Taxol pathway 10-O-acetyltransferase shows regioselective promiscuity with the oxetane hydroxyl of 4-deacetyltaxanes
Ondari, M. E.; Walker, K. D. J. Am. Chem. Soc. 2008, 130, 17187.

β-Styryl- and β-aryl-β-alanine products of phenylalanine aminomutase catalysis
Klettke, K. L.; Sanyal, S.; Mutatu, W.; Walker, K. D. J. Am. Chem. Soc. 2007, 129, 6988.
Received SYNFACT OF THE MONTH recognition (Synfacts 2007, 8, 0865-0865)

Expression of an acetyl-CoA synthase and a CoA-transferase in Escherichia coli to produce modified taxanes in vivo
Loncaric, C.; Ward, A. F.; Walker, K. D. Biotechnol. J. 2007, 2, 266.

Unusual mechanism for an aminomutase rearrangement: Retention of configuration at the migration termini
Mutatu, W.; Klettke, K. L.; Foster, C.; Walker, K. D.Biochemistry (ACS) 2007, 46, 9785.

Profiling a Taxol pathway 10β-acetyltransferase: Assessment of the specificity and the production of baccatin III by in vivo acetylation in E. coli
Loncaric, C.; Merriweather, E.; Walker, K. D. ACS Chem. Biol. 2006, 13, 309.

PATENT: Transacylases of the paclitaxel biosynthetic pathway in Taxus cuspidata
Croteau, R.B.; Walker, K.D.; Schoendorf, A.; Wildung, M.R. Patent No. 2003-415197, 7153676 2006, Washington State University Research Foundation, USA, 110 pp.

Cloning, heterologous expression, and characterization of a phenylalanine aminomutase involved in Taxol biosynthesis
Walker, K. D.; Klettke, K.; Akiyama, T.; Croteau, R. J. Biol. Chem. 2004, 279, 53947.

Regioselectivity of taxoid-O-acetyltransferases: Heterologous expression and characterization of a new taxadien-5α-ol-O-acetyltransferase
Chau, M; Walker, K.; Long, R.; Croteau, R. Arch. Biochem. Biophys. 2004, 430, 237-246

Random sequencing of an induced Taxus cell cDNA library for identification of clones involved in Taxol biosynthesis.
Jennewein, S.; Wildung M.R.; Chau, M; Walker, K.; Croteau, R. Proc. Nat. Acad. Sci., USA 2004, 101, 9149-9154.

Taxol biosynthesis: Molecular cloning and characterization of a cytochrome P450 taxoid 7β-hydroxylase.
Chau, M; Jennewein, S.; Walker, K.; Croteau, R. Chem. Biol. 2004, 11, 663-672.

Molecular cloning and heterologous expression of the C-13 phenylpropanoid side chain-CoA acyltransferase functioning in Taxol biosynthesis.
Walker, K.; Fujisaki S, Long, R; Croteau, R. Proc. Nat. Acad. Sci., USA 2002, 99, 12715-12720.

The final acylation step in Taxol biosynthesis: The cloning of the taxoid C13-side-chain N-benzoyltransferase from Taxus
Walker, K.; Long, R; Croteau, R. Proc. Nat. Acad. Sci., USA, 2002, 99, 9166-9171.

Taxol biosynthetic genes.
Walker, K.; Croteau, R. Phytochemistry 2001, 58, 5-11.

Molecular cloning of a benzoyl-CoA:taxane 2α-O-benzoyltransferase cDNA from Taxus and functional expression in Escherichia coli
Walker, K.; Croteau, R. Proc. Nat. Acad. Sci., USA 2000, 97, 13591-13596.

Molecular cloning of a 10-deacetylbaccatin III-10-O-acetyl transferase cDNA from Taxus and functional expression in Escherichia coli
Walker, K.; Croteau, R. Proc. Nat. Acad. Sci., USA 2000, 97, 583-587.

Molecular cloning of a taxa-4(20),11(12)-dien-5α-ol-O-acetyl transferase cDNA from Taxus and functional expression in Escherichia coli
Walker, K.; Schoendorf, A.; Croteau, R. Arch. Biochem. Biophys. 2000, 374, 371-380.

PATENT: cDNA clones for transacylases of the Taxol biosynthetic pathway.
Croteau, R.B.; Walker, K.D.; Schoendorf, A.; Wildung, M.R.; Hezari, M. 1999 , US and Foreign Patent, PCT Int. Appl. (2001), 162 pp.

Taxol biosynthesis: A review of some determinant steps.
Walker, K.; Croteau, R. Recent Advances in Phytochemistry 1999, 33, 31-50.

Partial purification and characterization of acetyl coenzyme A:taxa-4(20),11(12)-dien-5α-ol-O-acetyl transferase that catalyzes the first acylation step of Taxol biosynthesis.
Walker, K.; Ketchum, R.E.B.; Hezari, M; Gatfield, D; Goleniowski, M; Barthol, A; Croteau, R.Arch. Biochem. Biophys. 1999, 364, 273-279.

Detection of a phenylalanine aminomutase in cell-free extracts of Taxus brevifolia and preliminary characterization of its reaction.
Walker K.D.; Floss, H.G. J. Am. Chem. Soc. 1998,120, 5333-5334.

Biosynthetic studies of w-cycloheptyl fatty acids in Alicyclobacillus cycloheptanicus, formation of cycloheptanecarboxylic acid from phenylalanine and phenylacetic acid.
Moore, B.S.; Walker, K.D.; Tornus; I; Handa, S; Poralla, K; Floss, H.G. J. Org. Chem. 1997, 62, 2173-2185.

The use of stereospecifically labeled phenylpropanoid compounds o determine the steric course of key reaction steps in the biosynthesis of Taxol, hyoscyamine and cycloheptyl fatty acids.
Walker KD. 1997 Thesis, 142 pp.
The Biosynthesis of tropic acid: A reevaluation of the stereochemical course of the conversion of phenyllactate to tropate in Datura stramonium
Chesters, N.C.J.E.; Walker, K.; O'Hagan, D; Floss, HG. J. Am. Chem. Soc. 1996, 118, 925-926.

Biosynthetic studies on Taxol.
Fleming, P.E.; Floss, H.G.; Haertel, M; Knaggs, AR; Lansing, A; Mocek, U; Walker, K.D. Pure and Appl. Chem. 1994, 66, 2045-2048.

Genetic transformation of mature Taxus: An approach to genetically control the in vitro production of the anticancer drug, Taxol.
Han, K-Y.; Fleming, P.; Walker, K.; Loper, M.; Chilton, W.S.; Mocek, U.; Gordon, M.P.; Floss H.G. Plant Science 1994, 95, 187-196.

Chemical and microbiological analysis of vacuum-packed, pasteurized flaked imitation crabmeat.
Hollingworth, T.A.; Kaysner, C.A.; Colburn, K.G.; Sullivan, J.J.; Abeyta. C.; Walker, K.D.; Torkelson, J.D; Throm HR; and Wekell MM. J. Food Sci. 1991, 56, 164-167.

Selective determination of histamine by flow injection analysis.
Hungerford, J.M.; Walker, K.D.; Wekell, M.M.; LaRose, J.E.; Throm, H.R. Anal. Chem. 1990, 62, 1971-1976.

Determination of tri-n-butyltin in oysters by reaction-gas chromatography of hydride derivatives.
Hungerford, J.M.; Walker, K.D.; Torkelson, J.D.; Steinbrecher, K.; Wekell, M.M. Talanta 1990, 37, 975-979.