scholarly journals Substrate specificity and structure of human aminoadipate aminotransferase/kynurenine aminotransferase II

2008 ◽  
Vol 28 (4) ◽  
pp. 205-215 ◽  
Author(s):  
Qian Han ◽  
Tao Cai ◽  
Danilo A. Tagle ◽  
Howard Robinson ◽  
Jianyong Li
Keyword(s):  
Substrate Specificity ◽  
Catalytic Efficiency ◽  
Structural Basis ◽  
Substrate Affinity ◽  
Kinetic Properties ◽  
Amino Group ◽  
Kynurenine Aminotransferase ◽  
Broad Substrate Specificity ◽  
Systematic Assessment ◽  
The Brain

KAT (kynurenine aminotransferase) II is a primary enzyme in the brain for catalysing the transamination of kynurenine to KYNA (kynurenic acid). KYNA is the only known endogenous antagonist of the N-methyl-D-aspartate receptor. The enzyme also catalyses the transamination of aminoadipate to α-oxoadipate; therefore it was initially named AADAT (aminoadipate aminotransferase). As an endotoxin, aminoadipate influences various elements of glutamatergic neurotransmission and kills primary astrocytes in the brain. A number of studies dealing with the biochemical and functional characteristics of this enzyme exist in the literature, but a systematic assessment of KAT II addressing its substrate profile and kinetic properties has not been performed. The present study examines the biochemical and structural characterization of a human KAT II/AADAT. Substrate screening of human KAT II revealed that the enzyme has a very broad substrate specificity, is capable of catalysing the transamination of 16 out of 24 tested amino acids and could utilize all 16 tested α-oxo acids as amino-group acceptors. Kinetic analysis of human KAT II demonstrated its catalytic efficiency for individual amino-group donors and acceptors, providing information as to its preferred substrate affinity. Structural analysis of the human KAT II complex with α-oxoglutaric acid revealed a conformational change of an N-terminal fraction, residues 15–33, that is able to adapt to different substrate sizes, which provides a structural basis for its broad substrate specificity.

scholarly journals Structural basis for the broad substrate specificity of two acyl-CoA dehydrogenases FadE5 from mycobacteria

2020 ◽  
Vol 117 (28) ◽  
pp. 16324-16332
Author(s):  
Xiaobo Chen ◽  
Jiayue Chen ◽  
Bing Yan ◽  
Wei Zhang ◽  
Luke W. Guddat ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Mycobacterium Smegmatis ◽  
Hydrophobic Interactions ◽  
Carbon Chain ◽  
Structural Basis ◽  
Broad Substrate Specificity ◽  
Carbon Chains ◽  
Binding Cavity ◽  
Π Stacking Interaction ◽  
Acyl Coa Dehydrogenases

FadE, an acyl-CoA dehydrogenase, introduces unsaturation to carbon chains in lipid metabolism pathways. Here, we report that FadE5 fromMycobacterium tuberculosis(MtbFadE5) andMycobacterium smegmatis(MsFadE5) play roles in drug resistance and exhibit broad specificity for linear acyl-CoA substrates but have a preference for those with long carbon chains. Here, the structures ofMsFadE5 andMtbFadE5, in the presence and absence of substrates, have been determined. These reveal the molecular basis for the broad substrate specificity of these enzymes. FadE5 interacts with the CoA region of the substrate through a large number of hydrogen bonds and an unusual π–π stacking interaction, allowing these enzymes to accept both short- and long-chain substrates. Residues in the substrate binding cavity reorient their side chains to accommodate substrates of various lengths. Longer carbon-chain substrates make more numerous hydrophobic interactions with the enzyme compared with the shorter-chain substrates, resulting in a preference for this type of substrate.

scholarly journals WOR5, a Novel Tungsten-Containing Aldehyde Oxidoreductase from Pyrococcus furiosus with a Broad Substrate Specificity

2005 ◽  
Vol 187 (20) ◽  
pp. 7056-7061 ◽  
Author(s):  
Loes E. Bevers ◽  
Emile Bol ◽  
Peter-Leon Hagedoorn ◽  
Wilfred R. Hagen
Keyword(s):  
Substrate Specificity ◽  
Pyrococcus Furiosus ◽  
Catalytic Efficiency ◽  
Aromatic Aldehydes ◽  
Protein Subunit ◽  
Efficient Catalyst ◽  
Paramagnetic Resonance ◽  
Broad Substrate Specificity ◽  
Aldehyde Oxidoreductase ◽  
Redox Partner

ABSTRACT WOR5 is the fifth and last member of the family of tungsten-containing oxidoreductases purified from the hyperthermophilic archaeon Pyrococcus furiosus. It is a homodimeric protein (subunit, 65 kDa) that contains one [4Fe-4S] cluster and one tungstobispterin cofactor per subunit. It has a broad substrate specificity with a high affinity for several substituted and nonsubstituted aliphatic and aromatic aldehydes with various chain lengths. The highest catalytic efficiency of WOR5 is found for the oxidation of hexanal (V max = 15.6 U/mg, Km = 0.18 mM at 60°C). Hexanal-incubated enzyme exhibits S = 1/2 electron paramagnetic resonance signals from [4Fe-4S]1+ (g values of 2.08, 1.93, and 1.87) and W5+ (g values of 1.977, 1.906, and 1.855). Cyclic voltammetry of ferredoxin and WOR5 on an activated glassy carbon electrode shows a catalytic wave upon addition of hexanal, suggesting that ferredoxin can be a physiological redox partner. The combination of WOR5, formaldehyde oxidoreductase, and aldehyde oxidoreductase forms an efficient catalyst for the oxidation of a broad range of aldehydes in P. furiosus.

Structural and Kinetic Properties of the Aldehyde Dehydrogenase NahF, a Broad Substrate Specificity Enzyme for Aldehyde Oxidation

Biochemistry ◽  
2016 ◽  
Vol 55 (38) ◽  
pp. 5453-5463 ◽  
Author(s):  
Juliana B. Coitinho ◽  
Mozart S. Pereira ◽  
Débora M. A. Costa ◽  
Samuel L. Guimarães ◽  
Simara S. Araújo ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Aldehyde Dehydrogenase ◽  
Kinetic Properties ◽  
Broad Substrate Specificity ◽  
Aldehyde Oxidation

scholarly journals Catalytic Efficiency Diversification of Duplicate β-1,3-1,4-Glucanases from Neocallimastix patriciarum J11

2012 ◽  
Vol 78 (12) ◽  
pp. 4294-4300 ◽  
Author(s):  
Yu-Lung Hung ◽  
Hui-Jye Chen ◽  
Jeng-Chen Liu ◽  
Yo-Chia Chen
Keyword(s):  
Substrate Specificity ◽  
Catalytic Efficiency ◽  
Substrate Affinity ◽  
Transfer Event ◽  
Content Type ◽  
Close Phylogenetic Relationship ◽  
Neocallimastix Patriciarum ◽  
Rumen Fungus ◽  
Specific Activities ◽  
Streptococcus Equinus

ABSTRACTFour types of β-1,3-1,4 glucanase (β-glucanase, EC 3.2.1.73) genes, designatedbglA13,bglA16,bglA51, andbglM2, were found in the cDNA library ofNeocallimastix patriciarumJ11. All were highly homologous with each other and demonstrated a close phylogenetic relationship with and a similar codon bias toStreptococcus equinus. The presence of expansion and several predicted secondary structures in the 3′ untranslated regions (3′UTRs) ofbglA16andbglM2suggest that these two genes were duplicated recently, whereasbglA13andbglA16, which contain very short 3′UTRs, were replicated earlier. These findings indicate that the β-glucanase genes fromN. patriciarumJ11 may have arisen by horizontal transfer from the bacterium and subsequent duplication in the rumen fungus. β-Glucanase genes ofStreptococcus equinus,Ruminococcus albus7, andN. patriciarumJ11 were cloned and expressed byEscherichia coli. The recombinant β-glucanases cloned fromS. equinus,R. albus7, andN. patriciarumJ11 were endo-acting and had similar substrate specificity, but they demonstrated different properties in other tests. The specific activities and catalytic efficiency of the bacterial β-glucanases were also significantly lower than those of the fungal β-glucanases. Our results also revealed that the activities and some characteristics of enzymes were changed during the horizontal gene transfer event. The specific activities of the fungal β-glucanases ranged from 26,529 to 41,209 U/mg of protein when barley-derived β-glucan was used as the substrate. They also demonstrated similar pH and temperature optima, substrate specificity, substrate affinity, and hydrolysis patterns. Nevertheless, BglA16 and BglM2, two recently duplicated β-glucanases, showed much higherkcatvalues than others. These results support the notion that duplicated β-glucanase genes, namely,bglA16andbglM2, increase the reaction efficiency of β-glucanases and suggest that the catalytic efficiency of β-glucanase is likely to be a criterion determining the evolutionary fate of duplicate forms inN. patriciarumJ11.

scholarly journals Structural Basis for Broad Substrate Specificity in Higher Plant β-d-Glucan Glucohydrolases

2002 ◽  
Vol 14 (5) ◽  
pp. 1033-1052 ◽  
Author(s):  
Maria Hrmova ◽  
Ross De Gori ◽  
Brian J. Smith ◽  
Jon K. Fairweather ◽  
Hugues Driguez ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Structural Basis ◽  
Higher Plant ◽  
Broad Substrate Specificity

Deciphering the structural basis of the broad substrate specificity of myo-inositol monophosphatase (IMP) from Cicer arietinum

2020 ◽  
Vol 151 ◽  
pp. 967-975 ◽  
Author(s):  
Prakarsh K. Yadav ◽  
Prafull Salvi ◽  
Nitin Uttam Kamble ◽  
Bhanu Prakash Petla ◽  
Manoj Majee ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Cicer Arietinum ◽  
Structural Basis ◽  
Inositol Monophosphatase ◽  
Broad Substrate Specificity

scholarly journals Characterizing human α-1,6-fucosyltransferase (FUT8) substrate specificity and structural similarities with related fucosyltransferases

2020 ◽  
Vol 295 (50) ◽  
pp. 17027-17045
Author(s):  
Bhargavi M. Boruah ◽  
Renuka Kadirvelraj ◽  
Lin Liu ◽  
Annapoorani Ramiah ◽  
Chao Li ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Active Site ◽  
Secretory Pathway ◽  
Structural Features ◽  
Structural Basis ◽  
Substrate Affinity ◽  
Neonatal Lethality ◽  
Donor And Acceptor ◽  
Active Site Mutants ◽  
Core Fucosylation

Mammalian Asn-linked glycans are extensively processed as they transit the secretory pathway to generate diverse glycans on cell surface and secreted glycoproteins. Additional modification of the glycan core by α-1,6-fucose addition to the innermost GlcNAc residue (core fucosylation) is catalyzed by an α-1,6-fucosyltransferase (FUT8). The importance of core fucosylation can be seen in the complex pathological phenotypes of FUT8 null mice, which display defects in cellular signaling, development, and subsequent neonatal lethality. Elevated core fucosylation has also been identified in several human cancers. However, the structural basis for FUT8 substrate specificity remains unknown.Here, using various crystal structures of FUT8 in complex with a donor substrate analog, and with four distinct glycan acceptors, we identify the molecular basis for FUT8 specificity and activity. The ordering of three active site loops corresponds to an increased occupancy for bound GDP, suggesting an induced-fit folding of the donor-binding subsite. Structures of the various acceptor complexes were compared with kinetic data on FUT8 active site mutants and with specificity data from a library of glycan acceptors to reveal how binding site complementarity and steric hindrance can tune substrate affinity. The FUT8 structure was also compared with other known fucosyltransferases to identify conserved and divergent structural features for donor and acceptor recognition and catalysis. These data provide insights into the evolution of modular templates for donor and acceptor recognition among GT-B fold glycosyltransferases in the synthesis of diverse glycan structures in biological systems.

scholarly journals Structural basis for the broad substrate specificity of the human tyrosylprotein sulfotransferase-1

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Shinnosuke Tanaka ◽  
Toshiaki Nishiyori ◽  
Hidetaka Kojo ◽  
Reo Otsubo ◽  
Moe Tsuruta ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Structural Basis ◽  
Broad Substrate Specificity
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