Fluorescence quenching of model membranes. 3. Relationship between calcium adenosinetriphosphatase enzyme activity and the affinity of the protein for phosphatidylcholines with different acyl chain characteristics

Biochemistry ◽  
1981 ◽  
Vol 20 (7) ◽  
pp. 1949-1961 ◽  
Author(s):  
Martin Caffrey ◽  
Gerald W. Feigenson
Keyword(s):  
Enzyme Activity ◽  
Fluorescence Quenching ◽  
Acyl Chain ◽  
Model Membranes

Acidic interaction of the colicin A pore-forming domain with model membranes of Escherichia coli lipids results in a large perturbation of acyl chain order and stabilization of the bilayer

Biochemistry ◽  
1992 ◽  
Vol 31 (45) ◽  
pp. 11089-11094 ◽  
Author(s):  
Vincent Geli ◽  
Martijn C. Koorengevel ◽  
Rudy A. Demel ◽  
Claude Lazdunski ◽  
J. Antoinette Killian
Keyword(s):  
Escherichia Coli ◽  
Acyl Chain ◽  
Model Membranes ◽  
Large Perturbation ◽  
Chain Order

Investigations of Interactions Between Altretamine and Model Membranes: Spectroscopic and Calorimetric Analysis

2019 ◽  
Vol 14 (04) ◽  
pp. 197-215
Author(s):  
D. Bilge ◽  
N. Civelek ◽  
Z. Özçelik Çetinel
Keyword(s):  
Molecular Level ◽  
Acyl Chain ◽  
Spectroscopic Studies ◽  
Model Membranes ◽  
Head Group ◽  
Scanning Calorimetry ◽  
Calorimetric Analysis ◽  
Multilamellar Vesicles ◽  
Calorimetric Studies ◽  
Chain Lengths

Altretamine (ALT) is a Food and Drug Administration (FDA) approved antineoplastic drug particularly used for ovarian cancer. This study examined, at a molecular level, the interactions of the drug with model membranes composed of phospholipids with different acyl chain lengths and head group charges at varied ALT concentrations based on temperature. For this purpose, spectroscopic studies of the liposomes in multilamellar vesicles form were conducted by Fourier transform-infrared spectroscopy (FTIR) and their calorimetric studies were carried out by differential scanning calorimetry (DSC) techniques. The results of the study showed that ALT clearly interacted with lipids and that these interactions were more significant in multilamellar vesicles made up of short chain phospholipids. Moreover, the results suggested that ALT settled into the tail group region, in particular the region that formed the hydrophobic part of lipids, and this effects the whole section of the membranes including glycerol backbones and head groups. This study is expected to contribute, on molecular level, to the studies on the knowledge of the mechanism in cancer, which is still very much a dangerous disease, and its related treatment.

scholarly journals Functional role of catalytic triad and oxyanion hole-forming residues on enzyme activity of Escherichia coli thioesterase I/protease I/phospholipase L1

2006 ◽  
Vol 397 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Li-Chiun Lee ◽  
Ya-Lin Lee ◽  
Ruey-Jyh Leu ◽  
Jei-Fu Shaw
Keyword(s):  
Escherichia Coli ◽  
Enzyme Activity ◽  
Amino Acid ◽  
Water Molecule ◽  
Acyl Chain ◽  
Residual Activity ◽  
Catalytic Triad ◽  
The Other ◽  
Oxyanion Hole

Escherichia coli TAP (thioesterase I, EC 3.1.2.2) is a multifunctional enzyme with thioesterase, esterase, arylesterase, protease and lysophospholipase activities. Previous crystal structural analyses identified its essential amino acid residues as those that form a catalytic triad (Ser10-Asp154-His157) and those involved in forming an oxyanion hole (Ser10-Gly44-Asn73). To gain an insight into the biochemical roles of each residue, site-directed mutagenesis was employed to mutate these residues to alanine, and enzyme kinetic studies were conducted using esterase, thioesterase and amino-acid-derived substrates. Of the residues, His157 is the most important, as it plays a vital role in the catalytic triad, and may also play a role in stabilizing oxyanion conformation. Ser10 also plays a very important role, although the small residual activity of the S10A variant suggests that a water molecule may act as a poor substitute. The water molecule could possibly be endowed with the nucleophilic-attacking character by His157 hydrogen-bonding. Asp154 is not as essential compared with the other two residues in the triad. It is close to the entrance of the substrate tunnel, therefore it predominantly affects substrate accessibility. Gly44 plays a role in stabilizing the oxyanion intermediate and additionally in acyl-enzyme-intermediate transformation. N73A had the highest residual enzyme activity among all the mutants, which indicates that Asn73 is not as essential as the other mutated residues. The role of Asn73 is proposed to be involved in a loop75–80 switch-move motion, which is essential for the accommodation of substrates with longer acyl-chain lengths.

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