Cardiolipin (CL) is a kind of diphosphatidylglycerol lipid. Two phosphatidylglycerols connect with a glycerol backbone in the center to form a dimeric structure. So it has four alkyl groups and potentially carries two negative charges. As there are four distinct alkyl chains in cardiolipin, the potential for complexity of this molecule species is enormous. However, in most animal tissues, cardiolipin contains 18-carbon fatty alkyl chains with 2 unsaturated bonds on each of them. It has been proposed that the (18:2)4 acyl chain configuration is an important structural requirement for the high affinity of CL to inner membrane proteins in mammalian mitochondria. However, studies with isolated enzyme preparations indicate that its importance may vary depending on the protein examined.
Since there are two phosphates in the molecule, each of them can catch one proton. Although it has a symmetric structure, Ionizing one phosphate happens at a very different levels of acidity than ionizing both: pK1 =3 and pK2 > 7.5. So, under normal physiological conditions (wherein pH is around 7), the molecule may carry only one negative charge. The hydroxyl groups (–OH and –O-) on phosphate would form a stable intramolecular hydrogen bond with the centered glycerol’s hydroxyl group, thus forming a bicyclic resonance structure. This structure traps one proton, which is quite helpful for oxidative phosphorylation.
As the head group forms such compact bicycle structure, the head group area is quite small relative to the big tail region consist of 4 acyl chains. Based on this special structure, the fluorescent mitochondrial indicator, nonyl acridine orange (NAO) was introduced in 1982, and was later found to target mitochondria by binding to CL. NAO has a very large head and small tail structure which can compensate with cardiolipin’s small head large tail structure, and arrange in a highly ordered way. Several studies were published utilizing NAO both as a quantitative mitochondrial indicator and an indicator of CL content in mitochondria. However, it is found that NAO was influenced by membrane potential and/or the spatial arrangement of CL. so it's not proper to use NAO for CL or mitochondria quantitative studies of intact respiring mitochondria. But NAO still represents a simple method of assessing CL content.
Cardiolipin bicyclic structure
Structure of NAO
NAO & CL arranged in a highly ordered way
Read more about this topic: Cardiolipin
Other articles related to "structure":
... The cover of each issue serves as the first panel to the story ... Gibbons said, "The cover of the Watchmen is in the real world and looks quite real, but it's starting to turn into a comic book, a portal to another dimension." The covers were designed as close-ups that focused on a single detail with no human elements present ...
... Since the structure is cubic, as described below, the thermal contraction is isotropic - equal in all directions ... The structure of cubic zirconium tungstate consists of corner-sharing ZrO6 octahedral and WO4 tetrahedral structural units ... which involve the coupled rotation of the polyhedral units that make up the structure, and lead to contraction ...
... In terms of literary structure, Revelation consists of four visions, each involving John “seeing” the plan of God unveiled, with an epilogue that concludes the book ... In terms of content, the structure of Revelation is built around four successive groups of seven the messages to the seven churches the seven seals the seven trumpets and the seven bowl judgments ... Kenneth Strand asserts that symbols and phrases of Revelation are organized as a chiastic structure, a literary device used frequently in the Old Testament ...
2 ... Loving-kindness living Boaz and Ruth are models of an altruism for which the word "loving-kindness" has been coined (approximately translating Hebrew hesed) ...
321 kinematic structure is a design method for robotic arms (serial manipulators), invented by Donald L ... industrial robots, such as the PUMA, have a kinematic structure that deviates a little bit from the 321 structure ...
Famous quotes containing the word structure:
“For the structure that we raise,
Time is with materials filled;
Our to-days and yesterdays
Are the blocks with which we build.”
—Henry Wadsworth Longfellow (18091882)
“When a house is tottering to its fall,
The strain lies heaviest on the weakest part,
One tiny crack throughout the structure spreads,
And its own weight soon brings it toppling down.”
—Ovid (Publius Ovidius Naso)
“The question is still asked of women: How do you propose to answer the need for child care? That is an obvious attempt to structure conflict in the old terms. The questions are rather: If we as a human community want children, how does the total society propose to provide for them?”
—Jean Baker Miller (20th century)