Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Attenuation of channel kinetics and conductance by cholesterol: An interpretation using structural stress as a unifying concept (1995)
    Springer
    The journal of membrane biology 143 (1995), S. 51-63 
    Details
    ISSN: 1432-1424
    Keywords: Calcium-activated potassium channel ; Cholesterol ; Conductance ; Lateral elastic stress ; Lipid bilayers ; Lipid-channel interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The ubiquity of cholesterol in cell membranes and changes in its concentration during development, aging and in various diseases suggest that it plays an important role in modulating cell function. We examined this possibility by monitoring the effects of cholesterol on the activity of the calcium-activated potassium (BK) channel reconstituted into lipid bilayers from rat brain homogenates. Increasing the cholesterol concentration to 11% of total lipid weight resulted in a 70% reduction in channel mean open time and a reduction of the open probability of the channel by 80%. Channel conductance was reduced by 7%. Cholesterol is known to change the order state and the modulus of compressibility of bilayers. These physico-chemical changes may be translated into an overall increase in the structural stress in the bilayer, and this force may be transmitted to proteins residing therein. By examining the characteristics of the BK channel as a function of temperature, in the presence and absence of cholesterol, we were able to estimate the activation energy based on Arrhenius plots of channel kinetics. Cholesterol reduced the activation energy of the BK channel by 50% for the open to closed transition. This result is consistent with an increased stress energy in the bilayer and favors the channel moving into the closed state. Taken together, these data are consistent with a model in which cholesterol induces structural stress which enhances the transition from the open to the closed state of the channel. We suggest that this is an important mechanism for regulating the activity of membrane-integral proteins and therefore membrane function, and that the concept of structural stress may be relevant to understanding the modulation of ion channel activity in cell membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232523
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Lipid-ion channel interactions: Increasing phospholipid headgroup size but not ordering acyl chains alters reconstituted channel behavior (1995)
    Springer
    The journal of membrane biology 145 (1995), S. 13-19 
    Details
    ISSN: 1432-1424
    Keywords: Lipid-protein interactions ; Elastic stress ; Curvature stress ; Reconstituted potassium channel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We have recently shown (Chang et al., 1995) that lipid-channel interactions, exemplified by the effects of cholesterol on the calcium-activated potassium (BK) channel, profoundly affect channel properties. The present study further explores such interactions by monitoring changes in BK channel behavior after reconstitution into bilayers where the size of phospholipid (PL) headgroups is increased and where the freedom of motion (inverse order) of fatty acid chains is incremented. Increasing the PL headgroup cross-sectional area, from that of N-meth-DOPE to that of DOPC (an increase from ca. 60 to 70 Å2), is associated with a doubling of the channel mean opentime. Channel conductance, however, was unaffected. Increasing the order of the fatty acid chains, from that of DOPE to POPE and to that of DEPE, had no significant effect on channel properties (at 22°C). We interpret the changes reported here to reflect lipid-protein interactions through the induction of structural stress related to the headgroup structures of phospholipids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233303
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Microencapsulation Protects Immunoglobulin in Yolk (IgY) Specific against Helicobacter pylori Urease (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 67 (2002), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : Hens were intramuscularly (im) immunized on thighs by using urease (E.C. 3.5.1.5) from Helicobactor pylori as antigen. The specificity of IgY against urease of H. pylori increased gradually after initial immunization. The collected yolk was microencapsulated with 10% or 20%β-cyclodextrin (β-CD) and gum arabic by a spray-drier. Microencapsulation was effective in protecting the IgY activity against pepsin. Liposome prepared at the lecithin/ cholesterol ratio of 1/0.25 (mole/mole) displayed satisfactory encapsulation efficiency (69%) of IgY. Increase in cholesterol content in the liposomal structure exhibited a stronger protection effect of IgY against pepsin and acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2002.tb11351.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Influence of Pectinesterase Inhibitor from Jelly Fig (Ficus awkeotsang Makino) Achenes on Pectinesterases and Cloud Loss of Fruit Juices (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 67 (2002), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : Citrus and jelly fig achene pectinesterase (PE) (1 U/mL) activity was remarkably inhibited by PE inhibitor (PEI) (2 mg/mL) from jelly fig (Ficus awkeotsang Makino) achenes, in the absence or presence of 0- to 500-mM salts or 0 to 30% of sugars. Changes in temperature (20 to 40 °C) apparently decreased the activity of citrus PE in PE-PEI reaction mixture. Enzyme-activity curves for jelly fig PE alone and for that in combination with PEI were parallel. Activity of crude PEs (1 U/mL) from tomato, apple, asparagus, and guava was reduced remarkably. Cloud loss of fresh tomato juice, apple juice, and papaya juice was greatly inhibited by PEI (1 mg/mL) during 12-wk storage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2002.tb08860.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Isolation of Lysozyme from Hen Egg Albumen by Alcohol-Insoluble Cross-Linked Pea Pod Solid Ion-Exchange Chromatography (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 66 (2001), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : Albumen from hen eggs was diluted 3-fold with 0.05 M NaCl solution at pH 4.0 and was further treated with 30% ethanol for 8 h. The supernatant (77900 U/mg protein) thus obtained was further diluted (2.5-fold) with distilled water and its pH value was adjusted to 8.0 before being subjected to alcohol-insoluble cross-linked pea pod solid (AICLPPS) ion-exchange chromatography for lysozyme isolation. Results showed that AI-CLPPS ion-exchange chromatography increased the purification to 68-fold with a 72% lysozyme recovery from the starting albumen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2001.tb16086.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    De-esterification and Transacylation Reactions of Pectinesterase from Jelly Fig (Ficus awkeotsang Makino) Achenes (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 66 (2001), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : Pectinesterase (PE) was isolated from jelly fig (Ficus awkeotsang Makino) achenes, then the optimal conditions for de-esterification and transacylation reactions were determined. Molecular weight of pectin (DE = 62.8 %) when reacted with PE at pH 6.5 and 45 °C in 0.2 M NaCl for 20 min remarkably increased from the original 72 kDa to 410 kDa, as determined by Fractogel TSK 65(S) gel permeation chromatography. Prolonging the incubation time of pectin-PE mixtures to 2 and 4 h also increased the molecular weights of pectin. Therefore, transacylation reaction was considered to occur and to increase the molecular weight of pectins when de-esterification reaction was catalyzed by pectinesterase (PE).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2001.tb15178.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Characterization of Lactoferrin (LF) from Colostral Whey Using Anti-LF Antibody Immunoaffinity Chromatography (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 67 (2002), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : Lactoferrin (LF) in colostral whey was isolated by anti-LF immunoglobulin in yolk (IgY)-Sepharose 4B immunoaffinity chromatography, and parameters such as binding capacity (qm) and dissociation constant (Kd, × 10−6 M) of this immunoaffinity gel for LF were discussed. Purification folds for colostral whey I (from colostrum collected within 6 d of postpartum) and colostral whey II (from colostrum collected within 1 d of postpartum) by anti-LF IgY-immunoaffinity chromatography were 135.80 and 103.60, respectively. The recovery for LF in the same colostral whey sample by anti-LF IgY-immunoaffinity chromatography was 82 to 99 %. qm of anti-LF IgY-immunoaffinity gel for LF in colostral whey I and whey II were 0.372 and 0.272 mg LF/mL wet gel, respectively. Kd of anti-LF IgY-immunoaffinity gel for LF in colostral whey I was 1.594 × 10−6 M and II was 1.587 × 10−6 M.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2002.tb09442.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Thermal Stability of Bovine Milk Immunoglobulin G (IgG) and the Effect of Added Thermal Protectants on the Stability (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 65 (2000), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: D and z values and some thermodynamic parameters of immunoglobulin G (IgG) in phosphate buffer solution (PBS) (0.15 M NaCl/0.01 M phosphate buffer, pH 7.0) and colostral whey, with or without the presence of thermal protectants, were calculated in model systems. The D and z values for separated IgG in PBS were much lower than those for separated IgG in 20% glycerol, whey, and whey with 20% glycerol. IgG in colostral whey showed larger D and z values with the protectants. The heat denaturing rate constants at 70-82°C for separated IgG in PBS were larger than those of IgG in colostral whey; and the energies of activation for separated IgG in PBS, 0.2% glutamic acid, 10% whole milk, 20% maltose and 20% glycerol were also larger.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2000.tb15977.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Pectinesterase Inhibitor in Jelly Fig (Ficus awkeotsang Makino) Achenes (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 66 (2001), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : Intact and crushed jelly fig (Ficus awkeotsang Makino) achenes were extracted for various periods of time, and the changes in pectinesterase (PE) activities were determined. The activity of crude PE solution from intact achenes increased gradually reaching a maximum (12 U/mL) at approximately 12 h, while the PE from crushed achenes was maintained at about 0.2 to 0.3 U/mL throughout the extraction. However, a sharp decline in PE activity (0.3 U/mL) of crude PE solution from intact achenes was observed when extract from crushed achenes was added. Heating in 100 °C water did not affect the inhibition (95% to 97%) of crude extract from crushed achenes (PE Inhibitor extract) on pea-pod (Pisum sativum L.) shell PE activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2001.tb11321.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Properties of Liposomes Prepared with Various Lipids (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 67 (2002), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : Use of several lipids as an alternative to cholesterol to prepare stable liposomes was tried. Liposome prepared at 1/0.25 lecithin/stearic acid ratio exhibited better (55%) encapsulation efficiency (EE) of bovine serum albumin (BSA) than that (41%) prepared at 1/0.25 lecithin/cholesterol ratio. Liposomes showed the minimal released percentage of encapsulated BSA at pH 6. Storage at −20 °C caused serious damage to liposomes. Addition of α–tocopherol was effective in stabilizing liposomes. Liposomes, incorporated with α–amylase, prepared at 1/0.25 lecithin/cholesterol or stearic acid ratio were effective in protecting enzyme against acid (pH 2.8) and pepsin (15 mg/mL). Use of stearic acid, instead of cholesterol, would be feasible in preparing stable liposomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2002.tb08820.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...