Effects of Gln102Arg and Cys97Gly mutations on the structural specificity and stereospecificity of the L-lactate dehydrogenase from Bacillus stearothermophilus
作者:Helmut K. W. Kallwass、Marcel A. Luyten、Wendy Parris、Marvin Gold、Cyril M. Kay、J. Bryan Jones
DOI:10.1021/ja00038a016
日期:1992.6
The L-lactatedehydrogenase of Bacillusstearothermophilus (BSLDH) is a thermostable enzyme with considerable potential for applications in asymmetric synthesis. An understanding of the factors controlling its structural specificity and stereospecificity is therefore of interest. In this paper the effects of GIn 102→Arg and Cys97→Gly mutations have been evaluated. In a survey of thirteen 2-keto acids
Kinetic and Structural Analysis of Two Linkers in the Tautomerase Superfamily: Analysis and Implications
作者:Bert-Jan Baas、Brenda P. Medellin、Jake A. LeVieux、Kaci Erwin、Emily B. Lancaster、William H. Johnson、Tamer S. Kaoud、R. Yvette Moreno、Marieke de Ruijter、Patricia C. Babbitt、Yan Jessie Zhang、Christian P. Whitman
DOI:10.1021/acs.biochem.1c00220
日期:2021.6.8
The tautomerase superfamily (TSF) is a collection of enzymes and proteins that share a simple β–α–β structural scaffold. Most members are constructed from a single-core β–α–β motif or two consecutively fused β–α–β motifs in which the N-terminal proline (Pro-1) plays a key and unusual role as a catalytic residue. The cumulative evidence suggests that a gene fusion event took place in the evolution of the TSF followed by duplication (of the newly fused gene) to result in the diversification of activity that is seen today. Analysis of the sequence similarity network (SSN) for the TSF identified several linking proteins (“linkers”) whose similarity links subgroups of these contemporary proteins that might hold clues about structure–function relationship changes accompanying the emergence of new activities. A previously uncharacterized pair of linkers (designated N1 and N2) was identified in the SSN that connected the 4-oxalocrotonate tautomerase (4-OT) and cis-3-chloroacrylic acid dehalogenase (cis-CaaD) subgroups. N1, in the cis-CaaD subgroup, has the full complement of active site residues for cis-CaaD activity, whereas N2, in the 4-OT subgroup, lacks a key arginine (Arg-39) for canonical 4-OT activity. Kinetic characterization and nuclear magnetic resonance analysis show that N1 has activities observed for other characterized members of the cis-CaaD subgroup with varying degrees of efficiencies. N2 is a modest 4-OT but shows enhanced hydratase activity using allene and acetylene compounds, which might be due to the presence of Arg-8 along with Arg-11. Crystallographic analysis provides a structural context for these observations.
Kinetic and Structural Characterization of a Heterohexamer 4-Oxalocrotonate Tautomerase from <i>Chloroflexus aurantiacus</i> J-10-fl: Implications for Functional and Structural Diversity in the Tautomerase Superfamily,
作者:Elizabeth A. Burks、Christopher D. Fleming、Andrew D. Mesecar、Christian P. Whitman、Scott D. Pegan
DOI:10.1021/bi100502z
日期:2010.6.22
4-Oxalocrotonatetautomerase (4-OT) isozymes play prominent roles in the bacterial utilization of aromatic hydrocarbons as sole carbon sources. These enzymes catalyze the conversion of 2-hydroxy-2,4-hexadienedioate (or 2-hydroxymuconate) to 2-oxo-3-hexenedioate, where Pro-1 functions as a general base and shuttles a proton from the 2-hydroxyl group of the substrate to the C-5 position of the product
A thermodynamic investigation of some reactions involving prephenic acid
作者:N Kishore、M.J Holden、Y.B Tewari、R.N Goldberg
DOI:10.1006/jcht.1998.0444
日期:1999.2
ΔrHmo = − (74 ± 3) kJ· mol−1for the reference reaction: prephenate2−(aq) + NADox−(aq) + H2O(l) = 4-hydroxyphenylpyruvate−(aq) + NADred2−(aq) + HCO3−(aq) + H+(aq). Both results pertain toT = 298.15 K and ionic strengthI = 0. Benson estimates for the entropies lead to approximate values of the equilibrium constantsK ≈ 1·1026andK ≈ 1· 1012, respectively, for the above two reference reactions.
The thiaminediphosphate-dependent, branched-chain 2-keto aciddecarboxylase from Lactococcus lactis sup. cremoris B1157 (KdcA) is a new valuableenzyme for the synthesis of chiral 2-hydroxy ketones. The gene was cloned and the enzyme was expressed as an N-terminal hexahistidine fusion protein in Escherichia coli. It has a broad substrate range for the decarboxylation reaction including linear and