von Raycho Yonchev
Statistik und Sichtungsnachweis dieser Seite findet sich am Artikelende
| [1.] Ry/Fragment 009 01 - Diskussion Zuletzt bearbeitet: 2016-04-10 13:06:46 WiseWoman | Anézo 2003, Fragment, Gesichtet, KomplettPlagiat, Ry, SMWFragment, Schutzlevel sysop |
|
|
|
| Untersuchte Arbeit: Seite: 9, Zeilen: 1 ff. (entire page) |
Quelle: Anézo 2003 Seite(n): 21, 22, 24, Zeilen: 21:19ff; 22:1ff, 24:22-27 |
|---|---|
| [Operationally, membrane proteins have been divided into two major classes –] peripheral (or extrinsic) proteins and integral (or intrinsic) proteins. This classification is based on the nature of their association with the lipid bilayers. The distinction between peripheral and integral proteins does not clearly define the mode of attachment to the bilayers, but rather the relative strength of the attachment, or the harshness of the treatment required to release the protein from membrane.
Peripheral membrane proteins generally interact with the surface of the membrane only and are not integrated into the hydrophobic core of the lipid bilayers. They are thought to be weakly bound to the membrane surface by electrostatic interaction, either with the lipid headgroups or with other proteins. Such an association is rather loose and peripheral membrane proteins can be readily removed by washing the membrane, changing the ionic strength or the pH. Integral membrane proteins extend deeply into or completely through the lipid bilayers and are thus integrated into the bilayers structure. Generally they can be removed from the membrane only with detergents or stronger agents that disrupt the membrane structure. The portion of the protein integrated into the membrane is thus thermodynamically compatible with the hydrophobic core of the bilayers – one expects a preponderance of hydrophobic amino acid residues in the intramembranous portion of the protein. Integral membrane proteins can be further divided into two subclasses. Transmembrane proteins constitute one of these subclasses and, as their name implies, span the lipid bilayers of the membrane. The other subclass refers to anchored proteins. A portion of these proteins is embedded in the hydrophobic interior of the bilayers, without passing completely through the membrane. In most cases, the lipids provide a hydrophobic anchor by which the protein is attached to the membrane. I.1.2 Membrane models At the turn of the nineteenth century, Overton speculated on the lipid nature of biomembranes by observing a correlation between the rates at which various small molecules penetrate plant cells and their partition coefficients in an oil/water system [3]. 3. Overton, E. Vierteljahrsschr. Naturforsch. Ges. Zurich [sic] 1899, 44 , 88. |
[page 21]
Operationally, membrane proteins have been divided into two major classes: peripheral (or extrinsic) proteins and integral (or intrinsic) proteins. This classification is based on the nature of their association with the lipid bilayer. The distinction between peripheral and integral proteins does not clearly define the mode of attachment to the bilayer, but rather the relative strength of the attachment, or the harshness of the treatment required to release the protein from the membrane.
[page 22]
[page 24] 1.1.5 Membrane models This section gives a brief historical overview of the main stages that have contributed to the actual conception of membrane model. At the turn of the nineteenth century, Overton speculated on the lipid nature of biomembranes by observing a correlation between the rates at which various small molecules penetrate plant cells and their partition coefficients in an oil/water system [13]. [13] E. Overton. Vierteljahrsschr. Naturforsch. Ges. Zürich, 44:88–135, 1899. |
No source is given. |
|
Letzte Bearbeitung dieser Seite: durch Benutzer:WiseWoman, Zeitstempel: 20160410130820