Role of Membrane Lipids in Modulating the Activity of Membrane-Bound Enzymes

2004 ◽  
pp. 511-522
1975 ◽  
Vol 146 (2) ◽  
pp. 409-416 ◽  
Author(s):  
K Watson ◽  
R L Houghton ◽  
E Bertoli ◽  
D E Griffiths

The lipid composition of yeast cells was manipulated by the use of an unsaturated fatty acid auxotroph of Saccharomyces cerevisiae. There was a 2-3-fold decrease in the concentration of cytochromes a+a3 when the unsaturated fatty acid content of the cells was decreased from 60-70% of the total fatty acid to 20-30%. The amounts of cytochromes b and c were also decreased under these conditions, but to a lesser extent. Further lipid depletion, to proportions of less than 20% unsaturated fatty acid, led to a dramatic decrease in the content of all cytochromes, particularly cytochromes a+a3. The ATPase (adenosine triphosphatase), succinate oxidase and NADH oxidase activities of the isolated mitochondria also varied with the degree of unsaturation of the membrane lipids. The lower the percentage of unsaturated fatty acid, the lower was the enzymic activity. Inhibition of mitochondrial ATPase by oligomycin, on the other hand, was not markedly influenced by the membrane-lipid unsaturation. Npn-linear Arrenius plots of mitochondrial membrane-bound enzymes showed transition temperatures that were dependent on the degree of membrane-lipid unsaturation. The greater the degree of lipid unsaturation, the lower was the transition temperature. It was concluded that the degree of unsaturation of the membrane lipids plays an important role in determining the properties of mitochondrial membrane-bound enzymes.


2021 ◽  
Vol 14 (2) ◽  
pp. 85
Author(s):  
Antonio Laghezza ◽  
Luca Piemontese ◽  
Leonardo Brunetti ◽  
Alessia Caradonna ◽  
Mariangela Agamennone ◽  
...  

Matrix Metalloproteinases (MMPs) are a family of secreted and membrane-bound enzymes, of which 24 isoforms are known in humans. These enzymes degrade the proteins of the extracellular matrix and play a role of utmost importance in the physiological remodeling of all tissues. However, certain MMPs, such as MMP-2, -9, and -13, can be overexpressed in pathological states, including cancer and metastasis. Consequently, the development of MMP inhibitors (MMPIs) has been explored for a long time as a strategy to prevent and hinder metastatic growth, but the important side effects linked to promiscuous inhibition of MMPs prevented the clinical use of MMPIs. Therefore, several strategies were proposed to improve the therapeutic profile of this pharmaceutical class, including improved selectivity toward specific MMP isoforms and targeting of specific organs and tissues. Combining both approaches, we conducted the synthesis and preliminary biological evaluation of a series of (2-aminobenzothiazole)-methyl-1,1-bisphosphonic acids active as selective inhibitors of MMP-13 via in vitro and in silico studies, which could prove useful for the treatment of bone metastases thanks to the bone-targeting capabilities granted by the bisphosphonic acid group.


Biochemistry ◽  
1991 ◽  
Vol 30 (9) ◽  
pp. 2477-2482 ◽  
Author(s):  
Fausta Omodeo-Sale ◽  
Clara Lindi ◽  
Paola Palestini ◽  
Massimo Masserini

1983 ◽  
Vol 212 (2) ◽  
pp. 445-452 ◽  
Author(s):  
G Deliconstantinos ◽  
G Ramantanis

A marked increase in the activities of rat liver plasma-membrane (Na+ + K+)-stimulated ATPase and microsomal Ca2+-stimulated ATPase was observed 18h after partial hepatectomy. Lipid analyses for both membrane preparations reveal that in partially hepatectomized rats the cholesterol and sphingomyelin content are decreased with a subsequent decrease in the cholesterol/phospholipid molar ratio compared with those of sham-operated animals. Changes in the allosteric properties of plasma-membrane (Na+ + K+)-stimulated ATPase by F- (as reflected by changes in the Hill coefficient) indicated a fluidization of the lipid bilayer of both membrane preparations in 18 h-regenerating liver. The amphipathic dodecyl glucoside incorporated into the hepatic plasma membranes evoked a marked increase in the (Na+ + K+)-stimulated ATPase and 5′-nucleotidase activities. The lack of effect of the glucoside on the Lubrol-PX-solubilized 5′-nucleotidase indicates that changes in the activities of the membrane-bound enzymes caused by the glucoside are due to modulation of the membrane fluidity. Dodecyl glucoside appears to increase the membrane fluidity, evaluated through changes in the Hill coefficient for plasma-membrane (Na+ + K+)-stimulated ATPase. The biological significance of these data is discussed in terms of the differences and changes in the interaction of membrane-bound enzymes with membrane lipids during liver regeneration.


1979 ◽  
Vol 57 (9) ◽  
pp. 1144-1152 ◽  
Author(s):  
J. D. Vickers ◽  
M. P. Rathbone

The cholesterol content of normal human erythrocyte membranes (ghosts) was reduced by incubation of the ghosts with phosphatidylcholine (PC) liposomes for 4 h at 37 °C. As controls, ghosts were stored at 4 °C, incubated alone or incubated with PC liposomes saturated with cholesterol; none of these treatments altered membrane cholesterol content. The activities of three membrane-bound enzymes, spectrin kinase, band-3 protein kinase, and phospholipid kinase were reduced in cholesterol-depleted ghosts compared with control ghosts (p < 0.02, p < 0.05, and p < 0.01, respectively). Reductions of the protein kinase activities ranged from 5 to 30% and were apparently related to the extent of the reduction of ghost cholesterol content. The reduction of phospholipid kinase activity was greater (30–60%) and showed no correlation with the extent of reduction of ghost cholesterol content. In contrast to the kinase activities, the activity of a fourth enzyme, NADH: cytochrome c oxidoreductase, increased in response to membrane cholesterol depletion. The relationship between the increase in oxidoreductase activity and cholesterol depletion was best described as linear (r = 0.76).The data demonstrate that these enzyme activities are affected by membrane cholesterol content. Since the alterations in the enzyme activities caused by the artificial alterations of membrane cholesterol content were comparable with those observed in vivo in various pathological conditions, we suggest that the observed changes may be due to mechanisms whereby membrane lipids influence membrane enzyme activities in vivo.


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