scholarly journals A novel one-step process for enzymatic incorporation of amino acids into proteins: Papain-catalyzed polymerization of L-methionine ethyl ester and its regulation by adding a protein substrate.

1979 ◽  
Vol 43 (5) ◽  
pp. 1069-1074 ◽  
Author(s):  
Soichi ARAI ◽  
Michiko YAMASHITA ◽  
Masao FUJIMAKI
2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Melanie Mindt ◽  
Joe Max Risse ◽  
Hendrik Gruß ◽  
Norbert Sewald ◽  
Bernhard J. Eikmanns ◽  
...  

MRS Advances ◽  
2016 ◽  
Vol 1 (27) ◽  
pp. 1995-2001 ◽  
Author(s):  
Radovan Vukićević ◽  
Axel T. Neffe ◽  
Tim Gebauer ◽  
Oliver Frank ◽  
Michael Schossig ◽  
...  

ABSTRACTPreparation of three-dimensionally architectured porous biomaterials can be achieved in a one-step process by stabilizing gelatin with L-lysine diisocyanate ethyl ester (LDI) in water. The reaction of gelatin with LDI in presence of water leads to the formation of oligourea bridges between gelatin molecules and oligourea chains grafted on gelatin. The number and the length of the bridges, as well as of the grafted chains strongly depend on the concentration of the LDI used for the stabilization, and this has huge influence on the mechanical properties of the material on different hierarchical levels. Higher LDI concentrations yield materials with increased deformation resistance in tensile tests due to the higher number of covalent and physical netpoints in the material. However, mechanical properties determined on the micro-level by AFM indentation showed the opposite trend, i.e. a decrease of Young’s modulus with increasing LDI content. This was interpreted by a decreasing number of shorter oligourea bridges between gelatin chains with decreasing LDI content.


Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1649-1663
Author(s):  
Oliver Z Nanassy ◽  
Kelly T Hughes

Abstract The Hin recombinase catalyzes a site-specific recombination reaction that results in the reversible inversion of a 1-kbp segment of the Salmonella chromosome. The DNA inversion reaction catalyzed by the Salmonella Hin recombinase is a dynamic process proceeding through many intermediate stages, requiring multiple DNA sites and the Fis accessory protein. Biochemical analysis of this reaction has identified intermediate steps in the inversion reaction but has not yet revealed the process by which transition from one step to another occurs. Because transition from one reaction step to another proceeds through interactions between specific amino acids, and between amino acids and DNA bases, it is possible to study these transitions through mutational analysis of the proteins involved. We isolated a large number of mutants in the Hin recombinase that failed to carry out the DNA exchange reaction. We generated genetic tools that allowed the assignment of these mutants to specific transition steps in the recombination reaction. This genetic analysis, combined with further biochemical analysis, allowed us to define contributions by specific amino acids to individual steps in the DNA inversion reaction. Evidence is also presented in support of a model that Fis protein enhances the binding of Hin to the hixR recombination site. These studies identified regions within the Hin recombinase involved in specific transition steps of the reaction and provided new insights into the molecular details of the reaction mechanism.


Author(s):  
Shan Wang ◽  
Hai Deng

Abstract The introduction of β-hydroxy-α-amino acids (βHAAs) into organic molecules has received considerable attention as these molecules have often found widespread applications in bioorganic chemistry, medicinal chemistry and biomaterial science. Despite innovation of asymmetric synthesis of βHAAs, stereoselective synthesis to control the two chiral centres at Cα and Cβ positions is still challenging, with poor atomic economy and multi protection and deprotection steps. These syntheses are often operated under harsh conditions. Therefore, a biotransformation approach using biocatalysts is needed to selectively introduce these two chiral centres into structurally diverse molecules. Yet, there are few ways that enable one-step synthesis of βHAAs. One is to extend the substrate scope of the existing enzyme inventory. Threonine aldolases have been explored to produce βHAAs. However, the enzymes have poor controlled installation at Cβ position, often resulting in a mixture of diastereoisomers which are difficult to be separated. In this respect, l-threonine transaldolases (LTTAs) offer an excellent potential as the enzymes often provide controlled stereochemistry at Cα and Cβ positions. Another is to mine LTTA homologues and engineer the enzymes using directed evolution with the aim of finding engineered biocatalysts to accept broad substrates with enhanced conversion and stereoselectivity. Here, we review the development of LTTAs that incorporate various aldehyde acceptors to generate structurally diverse βHAAs and highlight areas for future developments. Key points • The general mechanism of the transaldolation reaction catalysed by LTTAs • Recent advances in LTTAs from different biosynthetic pathways • Applications of LTTAs as biocatalysts for production of βHAAs


Nanoscale ◽  
2021 ◽  
Author(s):  
Wipakorn Jevasuwan ◽  
Naoki Fukata

Vertical Al-catalyzed SiNW arrays with shaped surfaces were synthesized by a one-step process and NW-based solar cells were demonstrated with optimized NW surface defects through surface modification and length reduction.


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