Roles of Key Proline/Arginine Residues and Changes in Lipid Dynamics Reveal Interactions between the pH-Low Insertion Peptide (pHLIP) and Model Bilayers at Intermediate pH Values

2021 ◽  
Author(s):  
Sarah A. Otieno ◽  
Wei Qiang
Keyword(s):  
Ph Values ◽  
Lipid Dynamics ◽  
Arginine Residues

scholarly journals pH-dependent thermodynamic intermediates of pHLIP membrane insertion determined by solid-state NMR spectroscopy

2018 ◽  
Vol 115 (48) ◽  
pp. 12194-12199 ◽  
Author(s):  
Sarah A. Otieno ◽  
Samuel Z. Hanz ◽  
Bianca Chakravorty ◽  
Anqi Zhang ◽  
Lukas M. Klees ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Membrane Surface ◽  
Multistage Model ◽  
Solid State Nmr Spectroscopy ◽  
Ph Values ◽  
Lipid Dynamics ◽  
Ph Range ◽  
Α Helix

The applications of the pH low insertion peptide (pHLIP) in cancer diagnosis and cross-membrane cargo delivery have drawn increasing attention in the past decade. With its origin as the transmembrane (TM) helix C of bacteriorhodopsin, pHLIP is also an important model for understanding how pH can affect the folding and topogenesis of a TM α-helix. Protonations of multiple D/E residues transform pHLIP from an unstructured coil at membrane surface (known as state II, at pH ≥ 7) to a TM α-helix (state III, pH ≤ 5.3). While these initial and end states of pHLIP insertion have been firmly established, what happens at the intervening pH values is less clear. However, the intervening pH range is most relevant to pHLIP−cell interactions in the acidic extracellular tumor environment (and in the endosomes within cells). Here, using advanced solid-state NMR spectroscopy with palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine unilamellar vesicles as the model membrane, we systematically examined the state of pHLIP−membrane interactions (in terms of the membrane locations of D/E residues, as well as lipid dynamics) at the intervening pH values of 6.4, 6.1, and 5.8, along with the known states at pH 7.4 and 5.3. Thermodynamic intermediate states distinct from the initial and end states were discovered to exist at each of the intervening pH examined. They support a multistage model of pHLIP insertion in which the D/E titrations occur in a defined sequence at distinct intermediate pH values. This multistage model has important ramifications in pHLIP applications.

scholarly journals Subunit interactions in horse spleen apoferritin. Dissociation by extremes of pH

1973 ◽  
Vol 133 (2) ◽  
pp. 289-299 ◽  
Author(s):  
R. R. Crichton ◽  
Charles F. A. Bryce
Keyword(s):  
Conformational Changes ◽  
Difference Spectrum ◽  
Low Ph ◽  
Tryptophan Residue ◽  
Tyrosine Residues ◽  
Ph Values ◽  
Lysine Residues ◽  
Arginine Residues ◽  
The Difference ◽  
Ph Range

1. The dissociation of horse spleen apoferritin as a function of pH was analysed by sedimentation-velocity techniques. The oligomer is stable in the range pH2.8–10.6. Between pH2.8 and 1.6 and 10.6 and 13.0 both oligomer and subunits can be detected. At pH values between 1.6 and 1.0 the subunit is the only species observed, although below pH1.0 aggregation of the subunits to a particle sedimenting much faster than the oligomer occurs. 2. When apoferritin is first dissociated into subunits at low pH values and then dialysed into buffers of pH1.5–5.0, the subunit reassociates to oligomer in the pH range 3.1–4.3. 3. U.v.-difference spectroscopy was used to study conformational changes occurring during the dissociation process. The difference spectrum in acid can be accounted for by the transfer of four to five tyrosine residues/subunit from the interior of the protein into the solvent. This process is reversed on reassociation, but shows the same hysteresis as found by sedimentation techniques. The difference spectrum in alkali is more complex, but is consistent with the deprotonation of tyrosine residues, which appear to have rather high pK values. 4. In addition to the involvement of tyrosine residues in the conformational change at low pH values, spectral evidence is presented that one tryptophan residue/subunit also changes its environment before dissociation and subsequent to reassociation. 5. Analysis of the dissociation and reassociation of apoferritin at low pH values suggests that this is a co-operative process involving protonation and deprotonation of at least two carboxyl functions of rather low intrinsic pK. The dissociation at alkaline pH values does not appear to be co-operative. 6. Of the five tyrosine residues/subunit only one can be nitrated with tetranitromethane. Guanidination of lysine residues results in the modification of seven out of a total of nine residues/subunit. Nine out of the ten arginine residues/subunit react with cyclohexanedione.

Lipid dynamics in the annexin V - membrane complex

1999 ◽  
Vol 96 (9/10) ◽  
pp. 1602-1607
Author(s):  
O. Saurel ◽  
P. Demange ◽  
A. Lopez ◽  
A. Milon
Keyword(s):  
Annexin V ◽  
Membrane Complex ◽  
Lipid Dynamics

Evaluation of dissolution properties of silymarin capsules at different pH values

Planta Medica ◽  
2013 ◽  
Vol 79 (13) ◽  
Author(s):  
A Uzunovic ◽  
S Pilipovic ◽  
A Elezovic ◽  
A Sapcanin ◽  
O Rahic
Keyword(s):  
Ph Values ◽  
Dissolution Properties

The Disappearance of Heparin Activity with Liver Globulins and Determinations of Heparinase

1963 ◽  
Vol 10 (01) ◽  
pp. 071-080 ◽  
Author(s):  
L. B Jaques ◽  
C Mary Jaques
Keyword(s):  
Anticoagulant Activity ◽  
Rabbit Liver ◽  
Dissociation Curve ◽  
Ph Values ◽  
Phenol Extraction ◽  
Progressive Loss ◽  
Heparin Activity

SummaryPreparations were made of rabbit liver globulin by the method of Jaques for heparinase and their effect on heparin studied. The results confirmed the observations of a progressive loss of anticoagulant activity with globulin in 0.9% saline, of a loss of metachromatic activity after phenol extraction and the reversal of the latter by alkali. The latter observations were due to the solubility in phenol of heparin on combination with protein. With suitable preparations, a decrease in anticoagulant activity without decrease in metachromatic activity was observed, i.e. conversion of heparin to uroheparin. Loss of heparin due to combination with protein and resulting precipitation, solubility in phenol, etc. followed a protein pH-dissociation curve. Loss of heparin anticoagulant activity due to heparinase was maximal at pH 5.4. No loss of heparin occurred at pH values more acid than 5 or more alkaline than 7.

Investigation of Some Water Quality Parameters of Pond Water under Mymensingh Municipality

2015 ◽  
Vol 8 (1) ◽  
pp. 85-89
Author(s):  
F Zannat ◽  
MA Ali ◽  
MA Sattar
Keyword(s):  
Water Quality ◽  
Water Samples ◽  
Chemical Properties ◽  
Pond Water ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Urban Region ◽  
Mn Toxicity ◽  
Ph Values ◽  
Drinking Water Standard

A study was conducted to evaluate the water quality parameters of pond water at Mymensingh Urban region. The water samples were collected from 30 ponds located at Mymensingh Urban Region during August to October 2010. The chemical analyses of water samples included pH, EC, Na, K, Ca, S, Mn and As were done by standard methods. The chemical properties in pond water were found pH 6.68 to 7.14, EC 227 to 700 ?Scm-1, Na 15.57 to 36.00 ppm, K 3.83 to 16.16 ppm, Ca 2.01 to 7.29 ppm, S 1.61 to 4.67 ppm, Mn 0.33 to 0.684 ppm and As 0.0011 to 0.0059 ppm. The pH values of water samples revealed that water samples were acidic to slightly alkaline in nature. The EC value revealed that water samples were medium salinity except one sample and also good for irrigation. According to drinking water standard Mn toxicity was detected in pond water. Considering Na, Ca and S ions pond water was safe for irrigation and aquaculture. In case of K ion, all the samples were suitable for irrigation but unsuitable for aquaculture.J. Environ. Sci. & Natural Resources, 8(1): 85-89 2015

STRUKTUR KOMUNITAS MAKRO ALGA DI PESISIR PULAU KECAMATAN BULANG

SIMBIOSA ◽  
2014 ◽  
Vol 3 (2) ◽  
Author(s):  
Notowinarto Notowinarto ◽  
Ramses Ramses ◽  
Mulhairi Mulhairi
Keyword(s):  
Community Structure ◽  
Diversity Index ◽  
Algal Species ◽  
Algal Communities ◽  
Marine Life ◽  
Ph Values ◽  
Abundance Patterns ◽  
Coastal Marine ◽  
Temperature Parameter ◽  
Important Value Index

Bulang districts Batam Islands of  Riau province (Riau Islands), its consists of many islands with as well as having the potential diversity of coastal marine life in particular kinds of macro algae or seaweed. Conducted research aimed to determine the structure of macro- algal communities in the intertidal zone islands. The results of the identification of algal species found 16 species are: the Order of Chlorophyceae as 6 spesies; Order Phaeophyceae as 2 spesies; and Order Rhodophyceae as 8 spesies. The community structure at the five stations showed the highest values were found in the island of dominance Cicir (D ' = 0.79) , uniformity index values on Tengah Island (E ' = 0.99) , while the island Balak had the highest diversity index (H ' = 0.88) , with the abundance patterns of population structure on the island is pretty good Central . Results of correlation analysis of regression between IVI types of algae with the conditions of environmental quality suggests that there is a significance (Fhit ˃ F table and the value of r = > 90 %) between IVI algae Halimeda sp and Cryptarachne polyglandulosa at each station with a temperature parameter surface (⁰C) , depth temperature (⁰C) and pH values. Keywords : Algae, Community Structure, Important Value Index.

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