scholarly journals Structure-Based Alteration of Substrate Specificity and Catalytic Activity of Sulfite Oxidase from Sulfite Oxidation to Nitrate Reduction

Biochemistry ◽  
2012 ◽  
Vol 51 (6) ◽  
pp. 1134-1147 ◽  
Author(s):  
James A. Qiu ◽  
Heather L. Wilson ◽  
K. V. Rajagopalan
Keyword(s):  
Catalytic Activity ◽  
Substrate Specificity ◽  
Nitrate Reduction ◽  
Sulfite Oxidase ◽  
Sulfite Oxidation

scholarly journals Deacetoxycephalosporin C synthase isozymes exhibit diverse catalytic activity and substrate specificity

2003 ◽  
Vol 218 (2) ◽  
pp. 251-257 ◽  
Author(s):  
Hong Soon Chin ◽  
Janet Sim ◽  
Keng Ing Seah ◽  
Tiow Suan Sim
Keyword(s):  
Catalytic Activity ◽  
Substrate Specificity

scholarly journals A new dopachrome-rearranging enzyme from the ejected ink of the cuttlefish Sepia officinalis.

1994 ◽  
Vol 299 (3) ◽  
pp. 839-844 ◽  
Author(s):  
A Palumbo ◽  
M d'Ischia ◽  
G Misuraca ◽  
L De Martino ◽  
G Prota
Keyword(s):  
Catalytic Activity ◽  
Methyl Ester ◽  
Substrate Specificity ◽  
Molecular Mass ◽  
Significant Inhibition ◽  
Single Band ◽  
Pigment Cells ◽  
Sepia Officinalis ◽  
High Substrate ◽  
Sds Page

A melanogenic enzyme catalysing the rearrangement of dopachrome has been identified in the ejected ink of the cuttlefish Sepia officinalis. This enzyme occurs as a heat-labile protein which co-migrates with tyrosinase under a variety of chromatographic and electrophoretic conditions. On SDS/PAGE it shows like a single band with an approx. molecular mass of 85 kDa. The enzyme possesses high substrate specificity, acting on L-dopachrome (Km = 1 mM at pH 6.8) and on L-alpha-methyl-dopachrome, but not on D-dopachrome, L-dopachrome methyl ester, dopaminochrome and adrenochrome. Significant inhibition of the catalytic activity was observed with tropolone and L-mimosine. H.p.1.c. analysis of the enzyme-catalysed rearrangement of L-dopachrome revealed the quantitative formation of the decarboxylated product, 5,6-dihydroxyindole. These results point to marked differences between melanogenesis in cephalopod pigment cells and in melanocytes, which may have important implications in relation to the use of sepiomelanin as a model for studies of mammalian melanins.

scholarly journals Overexpression of a Maize Sulfite Oxidase Gene in Tobacco Enhances Tolerance to Sulfite Stress via Sulfite Oxidation and CAT-Mediated H2O2 Scavenging

PLoS ONE ◽  
2012 ◽  
Vol 7 (5) ◽  
pp. e37383 ◽  
Author(s):  
Zongliang Xia ◽  
Kaile Sun ◽  
Meiping Wang ◽  
Ke Wu ◽  
Hua Zhang ◽  
...  
Keyword(s):  
Sulfite Oxidase ◽  
Oxidase Gene ◽  
Sulfite Oxidation

scholarly journals One functional subunit is sufficient for catalytic activity and substrate specificity of Escherichia coli endoribonuclease III artificial heterodimers

FEBS Letters ◽  
2002 ◽  
Vol 518 (1-3) ◽  
pp. 93-96 ◽  
Author(s):  
Christian Conrad ◽  
Jens Guido Schmitt ◽  
Elena Evguenieva-Hackenberg ◽  
Gabriele Klug
Keyword(s):  
Escherichia Coli ◽  
Catalytic Activity ◽  
Substrate Specificity

scholarly journals Arabidopsis thaliana β1,2-xylosyltransferase: an unusual glycosyltransferase with the potential to act at multiple stages of the plant N-glycosylation pathway

2005 ◽  
Vol 388 (2) ◽  
pp. 515-525 ◽  
Author(s):  
Peter BENCÚR ◽  
Herta STEINKELLNER ◽  
Barbara SVOBODA ◽  
Jan MUCHA ◽  
Richard STRASSER ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Substrate Specificity ◽  
Metal Ion ◽  
Catalytic Domain ◽  
Protein Characterization ◽  
Reaction Products ◽  
Glycosylation Sites ◽  
Glycosylation Pathway ◽  
Multiple Stages

XylT (β1,2-xylosyltransferase) is a unique Golgi-bound glycosyltransferase that is involved in the biosynthesis of glycoprotein-bound N-glycans in plants. To delineate the catalytic domain of XylT, a series of N-terminal deletion mutants was heterologously expressed in insect cells. Whereas the first 54 residues could be deleted without affecting the catalytic activity of the enzyme, removal of an additional five amino acids led to the formation of an inactive protein. Characterization of the N-glycosylation status of recombinant XylT revealed that all three potential N-glycosylation sites of the protein are occupied by N-linked oligosaccharides. However, an unglycosylated version of the enzyme displayed substantial catalytic activity, demonstrating that N-glycosylation is not essential for proper folding of XylT. In contrast with most other glycosyltransferases, XylT is enzymatically active in the absence of added metal ions. This feature is not due to any metal ion directly associated with the enzyme. The precise acceptor substrate specificity of XylT was assessed with several physiologically relevant compounds and the xylosylated reaction products were subsequently tested as substrates of other Golgi-resident glycosyltransferases. These experiments revealed that the substrate specificity of XylT permits the enzyme to act at multiple stages of the plant N-glycosylation pathway.

scholarly journals Substrate specificity and catalytic efficiency of aldo-keto reductases with phospholipid aldehydes

2007 ◽  
Vol 405 (1) ◽  
pp. 95-105 ◽  
Author(s):  
Matthew Spite ◽  
Shahid P. Baba ◽  
Yonis Ahmed ◽  
Oleg A. Barski ◽  
Kanchan Nijhawan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Substrate Specificity ◽  
Reductase Activity ◽  
Catalytic Efficiency ◽  
Scavenger Receptors ◽  
Significant Activity ◽  
Oxidized Lipoproteins ◽  
Phosphatidic Acids ◽  
Chemotactic Factors ◽  
Small Intestinal

Phospholipid oxidation generates several bioactive aldehydes that remain esterified to the glycerol backbone (‘core’ aldehydes). These aldehydes induce endothelial cells to produce monocyte chemotactic factors and enhance monocyte–endothelium adhesion. They also serve as ligands of scavenger receptors for the uptake of oxidized lipoproteins or apoptotic cells. The biochemical pathways involved in phospholipid aldehyde metabolism, however, remain largely unknown. In the present study, we have examined the efficacy of the three mammalian AKR (aldo-keto reductase) families in catalysing the reduction of phospholipid aldehydes. The model phospholipid aldehyde POVPC [1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine] was efficiently reduced by members of the AKR1, but not by the AKR6 or the ARK7 family. In the AKR1 family, POVPC reductase activity was limited to AKR1A and B. No significant activity was observed with AKR1C enzymes. Among the active proteins, human AR (aldose reductase) (AKR1B1) showed the highest catalytic activity. The catalytic efficiency of human small intestinal AR (AKR1B10) was comparable with the murine AKR1B proteins 1B3 and 1B8. Among the murine proteins AKR1A4 and AKR1B7 showed appreciably lower catalytic activity as compared with 1B3 and 1B8. The human AKRs, 1B1 and 1B10, and the murine proteins, 1B3 and 1B8, also reduced C-7 and C-9 sn-2 aldehydes as well as POVPE [1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphoethanolamine]. AKR1A4, B1, B7 and B8 catalysed the reduction of aldehydes generated in oxidized C16:0-20:4 phosphatidylcholine with acyl, plasmenyl or alkyl linkage at the sn-1 position or C16:0-20:4 phosphatidylglycerol or phosphatidic acid. AKR1B1 displayed the highest activity with phosphatidic acids; AKR1A4 was more efficient with long-chain aldehydes such as 5-hydroxy-8-oxo-6-octenoyl derivatives, whereas AKR1B8 preferred phosphatidylglycerol. These results suggest that proteins of the AKR1A and B families are efficient phospholipid aldehyde reductases, with non-overlapping substrate specificity, and may be involved in tissue-specific metabolism of endogenous or dietary phospholipid aldehydes.

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