Lista de obras -

'Democratized' genomic enzymology web tools for functional assignment

scientific article published on 27 September 2018

1-methylthio-D-xylulose 5-phosphate methylsulfurylase: a novel route to 1-deoxy-D-xylulose 5-phosphate in Rhodospirillum rubrum

artículo científico publicado en 2012

A General Strategy for the Discovery of Metabolic Pathways: d-Threitol, l-Threitol, and Erythritol Utilization in Mycobacterium smegmatis

artículo científico publicado en 2015

A RubisCO-like protein links SAM metabolism with isoprenoid biosynthesis

artículo científico publicado en 2012

A Unique cis-3-Hydroxy-l-proline Dehydratase in the Enolase Superfamily

article

A bifunctional salvage pathway for two distinct S-adenosylmethionine by-products that is widespread in bacteria, including pathogenic Escherichia coli

scientific article published on 17 January 2020

A gold standard set of mechanistically diverse enzyme superfamilies

artículo científico publicado en 2006

ATP-binding Cassette (ABC) Transport System Solute-binding Protein-guided Identification of Novel d-Altritol and Galactitol Catabolic Pathways in Agrobacterium tumefaciens C58.

artículo científico publicado en 2015

Activation of R235A mutant orotidine 5'-monophosphate decarboxylase by the guanidinium cation: effective molarity of the cationic side chain of Arg-235

artículo científico publicado en 2010

An examination of the relationship between active site loop size and thermodynamic activation parameters for orotidine 5'-monophosphate decarboxylase from mesophilic and thermophilic organisms

artículo científico publicado en 2009

Assignment of function to a domain of unknown function: DUF1537 is a new kinase family in catabolic pathways for acid sugars

artículo científico publicado en 2016

Characterization of an l-Ascorbate Catabolic Pathway with Unprecedented Enzymatic Transformations

scientific article published on 14 January 2020

Computation-Facilitated Assignment of the Function in the Enolase Superfamily: A Regiochemically Distinct Galactarate Dehydratase from Oceanobacillus iheyensis ,

artículo científico publicado en 2009

Computational, Structural, and Kinetic Evidence That Vibrio vulnificus FrsA Is Not a Cofactor-Independent Pyruvate Decarboxylase

artículo científico publicado en 2013

Conformational Changes in Orotidine 5′-Monophosphate Decarboxylase: A Structure-Based Explanation for How the 5′-Phosphate Group Activates the Enzyme

artículo científico publicado en 2012

Conformational Changes in Orotidine 5′-Monophosphate Decarboxylase: “Remote” Residues That Stabilize the Active Conformation

artículo científico publicado en 2010

Correction to "A General Strategy for the Discovery of Metabolic Pathways: D-Threitol, L-Threitol, and Erythritol Utilization in Mycobacterium smegmatis".

artículo científico publicado en 2016

Crystal structure and functional assignment of YfaU, a metal ion dependent class II aldolase from Escherichia coli K12

artículo científico publicado en 2008

D-Ribulose 5-phosphate 3-epimerase: functional and structural relationships to members of the ribulose-phosphate binding (beta/alpha)8-barrel superfamily

artículo científico publicado en 2006

Discovery of a dipeptide epimerase enzymatic function guided by homology modeling and virtual screening

artículo científico publicado en 2008

Discovery of a novel L-lyxonate degradation pathway in Pseudomonas aeruginosa PAO1.

artículo científico publicado en 2014

Discovery of function in the enolase superfamily: D-mannonate and d-gluconate dehydratases in the D-mannonate dehydratase subgroup

scientific journal article

Discovery of new enzymes and metabolic pathways by using structure and genome context

artículo científico publicado en 2013

Discovery of novel bacterial queuine salvage enzymes and pathways in human pathogens

artículo científico publicado en 2019

Dissecting the total transition state stabilization provided by amino acid side chains at orotidine 5'-monophosphate decarboxylase: a two-part substrate approach

artículo científico publicado en 2008

Divergent evolution in enolase superfamily: strategies for assigning functions

artículo científico publicado en 2011

Divergent evolution in the enolase superfamily: the interplay of mechanism and specificity

artículo científico publicado en 2005

Editorial overview: Novel enzymes, coenzymes, and metabolic pathways

scientific article published on 26 November 2018

Enzymatic and structural characterization of rTSγ provides insights into the function of rTSβ

artículo científico publicado en 2014

Enzyme (re)design: lessons from natural evolution and computation

artículo científico publicado en 2009

Enzyme Architecture: Breaking Down the Catalytic Cage that Activates Orotidine 5'-Monophosphate Decarboxylase for Catalysis

scientific article published on 07 December 2018

Enzyme Function Initiative-Enzyme Similarity Tool (EFI-EST): A web tool for generating protein sequence similarity networks

artículo científico publicado en 2015

Enzyme architecture: deconstruction of the enzyme-activating phosphodianion interactions of orotidine 5'-monophosphate decarboxylase

artículo científico publicado en 2014

Epoxyqueuosine Reductase QueH in the Biosynthetic Pathway to tRNA Queuosine Is a Unique Metalloenzyme

artículo científico publicado en 2021

Evolution of Enzymatic Activities in the Enolase Superfamily: Stereochemically Distinct Mechanisms in Two Families of cis , cis -Muconate Lactonizing Enzymes † ‡

artículo científico publicado en 2009

Evolution of Enzymatic Activities in the Enolase Superfamily: l -Rhamnonate Dehydratase † ‡

artículo científico publicado en 2008

Evolution of enzymatic activities in the enolase superfamily: D-Mannonate dehydratase from Novosphingobium aromaticivorans

artículo científico publicado en 2007

Evolution of enzymatic activities in the enolase superfamily: D-tartrate dehydratase from Bradyrhizobium japonicum

scientific journal article

Evolution of enzymatic activities in the enolase superfamily: L-fuconate dehydratase from Xanthomonas campestris

scientific journal article

Evolution of enzymatic activities in the enolase superfamily: L-talarate/galactarate dehydratase from Salmonella typhimurium LT2

artículo científico publicado en 2007

Evolution of enzymatic activities in the enolase superfamily: N-succinylamino acid racemase and a new pathway for the irreversible conversion of D- to L-amino acids

article

Evolution of enzymatic activities in the enolase superfamily: galactarate dehydratase III from Agrobacterium tumefaciens C58

scientific journal article

Evolution of enzymatic activities in the enolase superfamily: structure of a substrate-liganded complex of the L-Ala-D/L-Glu epimerase from Bacillus subtilis

article

Evolution of enzymatic activities in the orotidine 5'-monophosphate decarboxylase suprafamily: crystallographic evidence for a proton relay system in the active site of 3-keto-L-gulonate 6-phosphate decarboxylase

artículo científico publicado en 2004

Evolution of enzymatic activities in the orotidine 5'-monophosphate decarboxylase suprafamily: enhancing the promiscuous D-arabino-hex-3-ulose 6-phosphate synthase reaction catalyzed by 3-keto-L-gulonate 6-phosphate decarboxylase.

artículo científico publicado en 2005

Evolution of enzymatic activities in the orotidine 5'-monophosphate decarboxylase suprafamily: mechanistic evidence for a proton relay system in the active site of 3-keto-L-gulonate 6-phosphate decarboxylase

artículo científico publicado en 2004

Evolution of enzymatic activities in the orotidine 5'-monophosphate decarboxylase suprafamily: structural basis for catalytic promiscuity in wild-type and designed mutants of 3-keto-L-gulonate 6-phosphate decarboxylase.

artículo científico publicado en 2005

Evolution of enzymatic activity in the enolase superfamily: functional studies of the promiscuous o-succinylbenzoate synthase from Amycolatopsis

artículo científico publicado en 2004

Evolution of enzymatic activity in the enolase superfamily: structural and mutagenic studies of the mechanism of the reaction catalyzed by o-succinylbenzoate synthase from Escherichia coli

artículo científico publicado en 2003

Evolution of enzymatic activity in the enolase superfamily: structural studies of the promiscuous o-succinylbenzoate synthase from Amycolatopsis

artículo científico publicado en 2004

Evolution of enzyme superfamilies

artículo científico publicado en 2006

Evolution of function in (β/α)8-barrel enzymes ⬇️

artículo científico publicado el 1 de abril de 2003

Evolution of structure and function in the o-succinylbenzoate synthase/N-acylamino acid racemase family of the enolase superfamily

artículo científico publicado en 2006

Evolutionary potential of (beta/alpha)8-barrels: functional promiscuity produced by single substitutions in the enolase superfamily

artículo científico publicado en 2003

Evolutionary potential of (beta/alpha)8-barrels: in vitro enhancement of a "new" reaction in the enolase superfamily

artículo científico publicado en 2005

Evolutionary potential of (beta/alpha)8-barrels: stepwise evolution of a "new" reaction in the enolase superfamily.

artículo científico publicado en 2007

Experimental strategies for functional annotation and metabolism discovery: targeted screening of solute binding proteins and unbiased panning of metabolomes.

artículo científico publicado en 2015

Formation and stability of a vinyl carbanion at the active site of orotidine 5'-monophosphate decarboxylase: pKa of the C-6 proton of enzyme-bound UMP

artículo científico publicado en 2008

Functional assignment of multiple catabolic pathways for D-apiose

artículo científico publicado en 2018

Galactaro δ-lactone isomerase: lactone isomerization by a member of the amidohydrolase superfamily

artículo científico publicado en 2014

Genomic Enzymology: Web Tools for Leveraging Protein Family Sequence-Function Space and Genome Context to Discover Novel Functions.

artículo científico publicado en 2017

Homologous (beta/alpha)8-barrel enzymes that catalyze unrelated reactions: orotidine 5'-monophosphate decarboxylase and 3-keto-L-gulonate 6-phosphate decarboxylase

artículo científico publicado en 2002

Homology models guide discovery of diverse enzyme specificities among dipeptide epimerases in the enolase superfamily

artículo científico publicado en 2012

Identification and characterization of a mandelamide hydrolase and an NAD(P)+-dependent benzaldehyde dehydrogenase from Pseudomonas putida ATCC 12633.

artículo científico publicado en 2003

Identification of the in vivo function of the high-efficiency D-mannonate dehydratase in Caulobacter crescentus NA1000 from the enolase superfamily.

artículo científico publicado en 2014

Integration of untargeted metabolomics with transcriptomics reveals active metabolic pathways

artículo científico publicado en 2014

Investigating the physiological roles of low-efficiency D-mannonate and D-gluconate dehydratases in the enolase superfamily: pathways for the catabolism of L-gulonate and L-idonate

artículo científico publicado en 2014

Investigating the role of a backbone to substrate hydrogen bond in OMP decarboxylase using a site-specific amide to ester substitution

artículo científico publicado en 2014

Mechanism of the Orotidine 5′-Monophosphate Decarboxylase-Catalyzed Reaction: Evidence for Substrate Destabilization ,

artículo científico publicado en 2009

Mechanism of the Orotidine 5′-Monophosphate Decarboxylase-Catalyzed Reaction: Importance of Residues in the Orotate Binding Site ⬇️

artículo científico publicado el 6 de septiembre de 2011

Mechanism of the orotidine 5'-monophosphate decarboxylase-catalyzed reaction: effect of solvent viscosity on kinetic constants

artículo científico publicado en 2009

Mechanisms of protein evolution and their application to protein engineering

artículo científico publicado en 2007

Mechanistic diversity in the RuBisCO superfamily: RuBisCO from Rhodospirillum rubrum is not promiscuous for reactions catalyzed by RuBisCO-like proteins

artículo científico publicado en 2012

Mechanistic diversity in the RuBisCO superfamily: a novel isomerization reaction catalyzed by the RuBisCO-like protein from Rhodospirillum rubrum

artículo científico publicado en 2008

Mechanistic diversity in the RuBisCO superfamily: the "enolase" in the methionine salvage pathway in Geobacillus kaustophilus

artículo científico publicado en 2007

Novel Metabolic Pathways and Regulons for Hexuronate Utilization in Proteobacteria

scientific article published on 20 December 2018

OMP decarboxylase: phosphodianion binding energy is used to stabilize a vinyl carbanion intermediate

artículo científico publicado en 2011

Orotidine 5'-monophosphate decarboxylase: transition state stabilization from remote protein-phosphodianion interactions

artículo científico publicado en 2012

Prediction and assignment of function for a divergent N-succinyl amino acid racemase

artículo científico publicado en 2007

Prediction and biochemical demonstration of a catabolic pathway for the osmoprotectant proline betaine.

artículo científico publicado en 2014

Prediction and characterization of enzymatic activities guided by sequence similarity and genome neighborhood networks

scientific journal article

Prediction of enzymatic pathways by integrative pathway mapping.

artículo científico publicado en 2018

Product deuterium isotope effect for orotidine 5'-monophosphate decarboxylase: evidence for the existence of a short-lived carbanion intermediate

artículo científico publicado en 2007

Product deuterium isotope effects for orotidine 5'-monophosphate decarboxylase: effect of changing substrate and enzyme structure on the partitioning of the vinyl carbanion reaction intermediate

artículo científico publicado en 2010

Proton transfer from C-6 of uridine 5'-monophosphate catalyzed by orotidine 5'-monophosphate decarboxylase: formation and stability of a vinyl carbanion intermediate and the effect of a 5-fluoro substituent

artículo científico publicado en 2012

Purification, crystallization and structural elucidation of D-galactaro-1,4-lactone cycloisomerase from Agrobacterium tumefaciens involved in pectin degradation

artículo científico publicado en 2016

Rate and Equilibrium Constants for an Enzyme Conformational Change during Catalysis by Orotidine 5'-Monophosphate Decarboxylase

artículo científico publicado en 2015

Role of a guanidinium cation-phosphodianion pair in stabilizing the vinyl carbanion intermediate of orotidine 5'-phosphate decarboxylase-catalyzed reactions

artículo científico publicado en 2013

Roles of small laccases from Streptomyces in lignin degradation

artículo científico publicado en 2014

Structural Basis for Substrate Specificity in Phosphate Binding (β/α) 8 -Barrels: d -Allulose 6-Phosphate 3-Epimerase from Escherichia coli K-12 † ‡

artículo científico publicado en 2008

Structural evidence for a 1,2-enediolate intermediate in the reaction catalyzed by 3-keto-L-gulonate 6-phosphate decarboxylase, a member of the orotidine 5'-monophosphate decarboxylase suprafamily

artículo científico publicado en 2003

Structure of D-ribulose 5-phosphate 3-epimerase from Synechocystis to 1.6 A resolution

artículo científico publicado en 2004

Structure of an ABC transporter solute-binding protein specific for the amino sugars glucosamine and galactosamine.

artículo científico publicado en 2016

Target selection and annotation for the structural genomics of the amidohydrolase and enolase superfamilies

artículo científico publicado en 2009

The EFI Web Resource for Genomic Enzymology Tools: Leveraging Protein, Genome, and Metagenome Databases to Discover Novel Enzymes and Metabolic Pathways

artículo científico publicado en 2019

The Enzyme Function Initiative

artículo científico publicado en 2011

Utilization of L-ascorbate by Escherichia coli K-12: assignments of functions to products of the yjf-sga and yia-sgb operons

artículo científico publicado en 2002

Lista de obras de

'Democratized' genomic enzymology web tools for functional assignment

1-methylthio-D-xylulose 5-phosphate methylsulfurylase: a novel route to 1-deoxy-D-xylulose 5-phosphate in Rhodospirillum rubrum

A General Strategy for the Discovery of Metabolic Pathways: d-Threitol, l-Threitol, and Erythritol Utilization in Mycobacterium smegmatis

A RubisCO-like protein links SAM metabolism with isoprenoid biosynthesis

A Unique cis-3-Hydroxy-l-proline Dehydratase in the Enolase Superfamily

A bifunctional salvage pathway for two distinct S-adenosylmethionine by-products that is widespread in bacteria, including pathogenic Escherichia coli

A gold standard set of mechanistically diverse enzyme superfamilies

ATP-binding Cassette (ABC) Transport System Solute-binding Protein-guided Identification of Novel d-Altritol and Galactitol Catabolic Pathways in Agrobacterium tumefaciens C58.

Activation of R235A mutant orotidine 5'-monophosphate decarboxylase by the guanidinium cation: effective molarity of the cationic side chain of Arg-235

An examination of the relationship between active site loop size and thermodynamic activation parameters for orotidine 5'-monophosphate decarboxylase from mesophilic and thermophilic organisms

Assignment of function to a domain of unknown function: DUF1537 is a new kinase family in catabolic pathways for acid sugars

Characterization of an l-Ascorbate Catabolic Pathway with Unprecedented Enzymatic Transformations

Computation-Facilitated Assignment of the Function in the Enolase Superfamily: A Regiochemically Distinct Galactarate Dehydratase from Oceanobacillus iheyensis ,

Computational, Structural, and Kinetic Evidence That Vibrio vulnificus FrsA Is Not a Cofactor-Independent Pyruvate Decarboxylase

Conformational Changes in Orotidine 5′-Monophosphate Decarboxylase: A Structure-Based Explanation for How the 5′-Phosphate Group Activates the Enzyme

Conformational Changes in Orotidine 5′-Monophosphate Decarboxylase: “Remote” Residues That Stabilize the Active Conformation

Correction to "A General Strategy for the Discovery of Metabolic Pathways: D-Threitol, L-Threitol, and Erythritol Utilization in Mycobacterium smegmatis".

Crystal structure and functional assignment of YfaU, a metal ion dependent class II aldolase from Escherichia coli K12

D-Ribulose 5-phosphate 3-epimerase: functional and structural relationships to members of the ribulose-phosphate binding (beta/alpha)8-barrel superfamily

Discovery of a dipeptide epimerase enzymatic function guided by homology modeling and virtual screening

Discovery of a novel L-lyxonate degradation pathway in Pseudomonas aeruginosa PAO1.

Discovery of function in the enolase superfamily: D-mannonate and d-gluconate dehydratases in the D-mannonate dehydratase subgroup

Discovery of new enzymes and metabolic pathways by using structure and genome context

Discovery of novel bacterial queuine salvage enzymes and pathways in human pathogens

Dissecting the total transition state stabilization provided by amino acid side chains at orotidine 5'-monophosphate decarboxylase: a two-part substrate approach

Divergent evolution in enolase superfamily: strategies for assigning functions

Divergent evolution in the enolase superfamily: the interplay of mechanism and specificity

Editorial overview: Novel enzymes, coenzymes, and metabolic pathways

Enzymatic and structural characterization of rTSγ provides insights into the function of rTSβ

Enzyme (re)design: lessons from natural evolution and computation

Enzyme Architecture: Breaking Down the Catalytic Cage that Activates Orotidine 5'-Monophosphate Decarboxylase for Catalysis

Enzyme Function Initiative-Enzyme Similarity Tool (EFI-EST): A web tool for generating protein sequence similarity networks

Enzyme architecture: deconstruction of the enzyme-activating phosphodianion interactions of orotidine 5'-monophosphate decarboxylase

Epoxyqueuosine Reductase QueH in the Biosynthetic Pathway to tRNA Queuosine Is a Unique Metalloenzyme

Evolution of Enzymatic Activities in the Enolase Superfamily: Stereochemically Distinct Mechanisms in Two Families of cis , cis -Muconate Lactonizing Enzymes † ‡

Evolution of Enzymatic Activities in the Enolase Superfamily: l -Rhamnonate Dehydratase † ‡

Evolution of enzymatic activities in the enolase superfamily: D-Mannonate dehydratase from Novosphingobium aromaticivorans

Evolution of enzymatic activities in the enolase superfamily: D-tartrate dehydratase from Bradyrhizobium japonicum

Evolution of enzymatic activities in the enolase superfamily: L-fuconate dehydratase from Xanthomonas campestris

Evolution of enzymatic activities in the enolase superfamily: L-talarate/galactarate dehydratase from Salmonella typhimurium LT2

Evolution of enzymatic activities in the enolase superfamily: N-succinylamino acid racemase and a new pathway for the irreversible conversion of D- to L-amino acids

Evolution of enzymatic activities in the enolase superfamily: galactarate dehydratase III from Agrobacterium tumefaciens C58

Evolution of enzymatic activities in the enolase superfamily: structure of a substrate-liganded complex of the L-Ala-D/L-Glu epimerase from Bacillus subtilis

Evolution of enzymatic activities in the orotidine 5'-monophosphate decarboxylase suprafamily: crystallographic evidence for a proton relay system in the active site of 3-keto-L-gulonate 6-phosphate decarboxylase

Evolution of enzymatic activities in the orotidine 5'-monophosphate decarboxylase suprafamily: enhancing the promiscuous D-arabino-hex-3-ulose 6-phosphate synthase reaction catalyzed by 3-keto-L-gulonate 6-phosphate decarboxylase.

Evolution of enzymatic activities in the orotidine 5'-monophosphate decarboxylase suprafamily: mechanistic evidence for a proton relay system in the active site of 3-keto-L-gulonate 6-phosphate decarboxylase

Evolution of enzymatic activities in the orotidine 5'-monophosphate decarboxylase suprafamily: structural basis for catalytic promiscuity in wild-type and designed mutants of 3-keto-L-gulonate 6-phosphate decarboxylase.

Evolution of enzymatic activity in the enolase superfamily: functional studies of the promiscuous o-succinylbenzoate synthase from Amycolatopsis

Evolution of enzymatic activity in the enolase superfamily: structural and mutagenic studies of the mechanism of the reaction catalyzed by o-succinylbenzoate synthase from Escherichia coli

Evolution of enzymatic activity in the enolase superfamily: structural studies of the promiscuous o-succinylbenzoate synthase from Amycolatopsis

Evolution of enzyme superfamilies

Evolution of function in (β/α)8-barrel enzymes ⬇️

Evolution of structure and function in the o-succinylbenzoate synthase/N-acylamino acid racemase family of the enolase superfamily

Evolutionary potential of (beta/alpha)8-barrels: functional promiscuity produced by single substitutions in the enolase superfamily

Evolutionary potential of (beta/alpha)8-barrels: in vitro enhancement of a "new" reaction in the enolase superfamily

Evolutionary potential of (beta/alpha)8-barrels: stepwise evolution of a "new" reaction in the enolase superfamily.

Experimental strategies for functional annotation and metabolism discovery: targeted screening of solute binding proteins and unbiased panning of metabolomes.

Formation and stability of a vinyl carbanion at the active site of orotidine 5'-monophosphate decarboxylase: pKa of the C-6 proton of enzyme-bound UMP

Functional assignment of multiple catabolic pathways for D-apiose

Galactaro δ-lactone isomerase: lactone isomerization by a member of the amidohydrolase superfamily

Genomic Enzymology: Web Tools for Leveraging Protein Family Sequence-Function Space and Genome Context to Discover Novel Functions.

Homologous (beta/alpha)8-barrel enzymes that catalyze unrelated reactions: orotidine 5'-monophosphate decarboxylase and 3-keto-L-gulonate 6-phosphate decarboxylase

Homology models guide discovery of diverse enzyme specificities among dipeptide epimerases in the enolase superfamily

Identification and characterization of a mandelamide hydrolase and an NAD(P)+-dependent benzaldehyde dehydrogenase from Pseudomonas putida ATCC 12633.

Identification of the in vivo function of the high-efficiency D-mannonate dehydratase in Caulobacter crescentus NA1000 from the enolase superfamily.

Integration of untargeted metabolomics with transcriptomics reveals active metabolic pathways

Investigating the physiological roles of low-efficiency D-mannonate and D-gluconate dehydratases in the enolase superfamily: pathways for the catabolism of L-gulonate and L-idonate

Investigating the role of a backbone to substrate hydrogen bond in OMP decarboxylase using a site-specific amide to ester substitution

Mechanism of the Orotidine 5′-Monophosphate Decarboxylase-Catalyzed Reaction: Evidence for Substrate Destabilization ,

Mechanism of the Orotidine 5′-Monophosphate Decarboxylase-Catalyzed Reaction: Importance of Residues in the Orotate Binding Site ⬇️

Mechanism of the orotidine 5'-monophosphate decarboxylase-catalyzed reaction: effect of solvent viscosity on kinetic constants

Mechanisms of protein evolution and their application to protein engineering

Mechanistic diversity in the RuBisCO superfamily: RuBisCO from Rhodospirillum rubrum is not promiscuous for reactions catalyzed by RuBisCO-like proteins

Mechanistic diversity in the RuBisCO superfamily: a novel isomerization reaction catalyzed by the RuBisCO-like protein from Rhodospirillum rubrum

Mechanistic diversity in the RuBisCO superfamily: the "enolase" in the methionine salvage pathway in Geobacillus kaustophilus

Novel Metabolic Pathways and Regulons for Hexuronate Utilization in Proteobacteria

OMP decarboxylase: phosphodianion binding energy is used to stabilize a vinyl carbanion intermediate

Orotidine 5'-monophosphate decarboxylase: transition state stabilization from remote protein-phosphodianion interactions

Prediction and assignment of function for a divergent N-succinyl amino acid racemase