Interactions ofStreptomyces griseus aminopeptidase with amino acid reaction products and their implications toward a catalytic mechanism

2001 ◽  
Vol 44 (4) ◽  
pp. 490-504 ◽  
Author(s):  
R. Gilboa ◽  
A. Spungin-Bialik ◽  
G. Wohlfahrt ◽  
D. Schomburg ◽  
S. Blumberg ◽  
...  
Keyword(s):  
Amino Acid ◽  
Catalytic Mechanism ◽  
Reaction Products ◽  
Acid Reaction

Effect of Oxidized Lipid/Amino Acid Reaction Products on the Antioxidative Activity of Common Antioxidants

1998 ◽  
Vol 46 (9) ◽  
pp. 3768-3771 ◽  
Author(s):  
Ishtiaque Ahmad ◽  
Manuel Alaiz ◽  
Rosario Zamora ◽  
Francisco J. Hidalgo
Keyword(s):  
Amino Acid ◽  
Antioxidative Activity ◽  
Reaction Products ◽  
Acid Reaction

Feed-Back Inhibition of Oxidative Stress by Oxidized Lipid/Amino Acid Reaction Products†

Biochemistry ◽  
1997 ◽  
Vol 36 (50) ◽  
pp. 15765-15771 ◽  
Author(s):  
Rosario Zamora ◽  
Manuel Alaiz ◽  
Francisco J. Hidalgo
Keyword(s):  
Oxidative Stress ◽  
Amino Acid ◽  
Reaction Products ◽  
Acid Reaction

scholarly journals The levansucrase and inulosucrase enzymes of Lactobacillus reuteri 121 catalyse processive and non-processive transglycosylation reactions

Microbiology ◽  
2006 ◽  
Vol 152 (4) ◽  
pp. 1187-1196 ◽  
Author(s):  
Lukasz K. Ozimek ◽  
Slavko Kralj ◽  
Marc J. E. C. van der Maarel ◽  
Lubbert Dijkhuizen
Keyword(s):  
Amino Acid ◽  
Catalytic Mechanism ◽  
Lactobacillus Reuteri ◽  
Amino Acid Residues ◽  
Reaction Products ◽  
Detailed Characterization ◽  
Amino Acid Sequence Level ◽  
Chain Polymerization ◽  
Binding Subsites

Bacterial fructosyltransferase (FTF) enzymes synthesize fructan polymers from sucrose. FTFs catalyse two different reactions, depending on the nature of the acceptor, resulting in: (i) transglycosylation, when the growing fructan chain (polymerization), or mono- and oligosaccharides (oligosaccharide synthesis), are used as the acceptor substrate; (ii) hydrolysis, when water is used as the acceptor. Lactobacillus reuteri 121 levansucrase (Lev) and inulosucrase (Inu) enzymes are closely related at the amino acid sequence level (86 % similarity). Also, the eight amino acid residues known to be involved in catalysis and/or sucrose binding are completely conserved. Nevertheless, these enzymes differ markedly in their reaction and product specificities, i.e. in β(2→6)- versus β(2→1)-glycosidic-bond specificity (resulting in levan and inulin synthesis, respectively), and in the ratio of hydrolysis versus transglycosylation activities [resulting in glucose and fructooligosaccharides (FOSs)/polymer synthesis, respectively]. The authors report a detailed characterization of the transglycosylation reaction products synthesized by the Lb. reuteri 121 Lev and Inu enzymes from sucrose and related oligosaccharide substrates. Lev mainly converted sucrose into a large levan polymer (processive reaction), whereas Inu synthesized mainly a broad range of FOSs of the inulin type (non-processive reaction). Interestingly, the two FTF enzymes were also able to utilize various inulin-type FOSs (1-kestose, 1,1-nystose and 1,1,1-kestopentaose) as substrates, catalysing a disproportionation reaction; to the best of our knowledge, this has not been reported for bacterial FTF enzymes. Based on these data, a model is proposed for the organization of the sugar-binding subsites in the two Lb. reuteri 121 FTF enzymes. This model also explains the catalytic mechanism of the enzymes, and differences in their product specificities.

Addition of Oxidized Lipid/Amino Acid Reaction Products Delays the Peroxidation Initiated in a Soybean Oil

1995 ◽  
Vol 43 (10) ◽  
pp. 2698-2701 ◽  
Author(s):  
Manuel Alaiz ◽  
Rosario Zamora ◽  
Francisco J. Hidalgo
Keyword(s):  
Amino Acid ◽  
Soybean Oil ◽  
Reaction Products ◽  
Acid Reaction

Chemically Selective Reactions in Confined Spaces in Hybrid Aerogels

2005 ◽  
Vol 899 ◽  
Author(s):  
Xipeng Liu ◽  
Chunhua Yao ◽  
William M Risen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Metal Ions ◽  
Chemical Reactions ◽  
Reaction Products ◽  
Spatial Confinement ◽  
Confined Spaces ◽  
Hybrid Silica ◽  
Hybrid Aerogels ◽  
Chemically Selective

AbstractBy employing novel hybrid silica/functional polymer aerogels, control of the course of chemical reactions between reactants confined inside of the aerogels with reactants whose access to the confinement domain is controlled by diffusion has been explored. Thus, monolithic silica/biopolymer hybrid aerogels have been synthesized with coordinated metal ions that can react with amino acids, such as L-cysteine, that are provided externally in a surrounding solution. Metal ions, such as Au(III), that can react in solution with the amino acid to produce one set of products under a given set of stoichiometric or concentration conditions, and a different set of products under a second set of conditions, were selected for incorporation into the aerogel. It was discovered that the course of the reaction can be changed by spatial confinement of the reaction domain in the aerogel. For example, in the case of Au(III) and L-cysteine, the Au(III) ions are confined in nanoscale domains, and when they are reacted with the amino acid, the nature of the reaction products is controlled by diffusion of the L-cysteine into the domains. Exploration of these and related phenomena will be presented.

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