Difference between revisions of "Malate"
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|abbr=M | |abbr=M | ||
|description=[[File:Malic_acid.jpg|left|100px|Malic acid]] | |description=[[File:Malic_acid.jpg|left|100px|Malic acid]] | ||
'''Malic acid''', C<sub>4</sub>H<sub>6</sub>O<sub>5</sub>, occurs under physiological conditions as the anion '''malate, M''', with ''p''K<sub>a1</sub> = 3.40 and ''p''K<sub>a2</sub> = 5.20. L-Malate is formed from [[fumarate]] in the [[ | '''Malic acid''', C<sub>4</sub>H<sub>6</sub>O<sub>5</sub>, occurs under physiological conditions as the anion '''malate<sup>2-</sup>, M''', with ''p''K<sub>a1</sub> = 3.40 and ''p''K<sub>a2</sub> = 5.20. L-Malate is formed from [[fumarate]] in the [[TCA cycle]] in the mitochondrial matrix, where it is the substrate of [[malate dehydrogenase]] oxidized to [[oxaloacetate]]. Malate is also formed in the cytosol. It cannot permeate through the lipid bilayer of membranes and hence requires a carrier ([[dicarboxylate carrier]], [[tricarboxylate carrier]] and [[2-oxoglutarate carrier]]). Malate alone cannot support respiration of [[Mitochondrial preparations|mt-preparations]] from most tissues, since oxaloacetate accumulates in the absence of [[pyruvate]] or [[glutamate]]. | ||
|info=[http://www.oroboros.at/?Gnaiger_2012_MitoPathways Gnaiger 2012 MitoPathways], [[MiPNet09.12 O2k-Titrations]] | |info=[http://www.oroboros.at/?Gnaiger_2012_MitoPathways Gnaiger 2012 MitoPathways], [[MiPNet09.12 O2k-Titrations]] | ||
|type=Respiration | |type=Respiration | ||
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'''Preparation of 400 mM stock solution''' (dissolved in H<sub>2</sub>O): | '''Preparation of 400 mM stock solution''' (dissolved in H<sub>2</sub>O): | ||
::1) Weigh 268.2 mg of L- | ::1) Weigh 268.2 mg of L-malic acid. | ||
::2) Add 3 ml H<sub>2</sub>O. | ::2) Add 3 ml H<sub>2</sub>O. | ||
::3) Neutralize with 10 N KOH (approx. 350 µl). | ::3) Neutralize with 10 N KOH (approx. 350 µl). | ||
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'''Oxygraph-2k manual titrations:''' [[MiPNet09.12 O2k-Titrations]] | '''Oxygraph-2k manual titrations:''' [[MiPNet09.12 O2k-Titrations]] | ||
::* Titration volume: 2.5 µl using a | ::* Titration volume: 2.5 µl using a 25 µl Hamilton syringe. | ||
::* Final conc. in 2 ml O2k-chamber: 0.5 mM. | ::* Final conc. in 2 ml O2k-chamber: 0.5 mM. | ||
Revision as of 08:28, 15 April 2014
- high-resolution terminology - matching measurements at high-resolution
Malate
Description
Malic acid, C4H6O5, occurs under physiological conditions as the anion malate2-, M, with pKa1 = 3.40 and pKa2 = 5.20. L-Malate is formed from fumarate in the TCA cycle in the mitochondrial matrix, where it is the substrate of malate dehydrogenase oxidized to oxaloacetate. Malate is also formed in the cytosol. It cannot permeate through the lipid bilayer of membranes and hence requires a carrier (dicarboxylate carrier, tricarboxylate carrier and 2-oxoglutarate carrier). Malate alone cannot support respiration of mt-preparations from most tissues, since oxaloacetate accumulates in the absence of pyruvate or glutamate.
Abbreviation: M
Reference: Gnaiger 2012 MitoPathways, MiPNet09.12 O2k-Titrations
MitoPedia topics: Substrate and metabolite
Application in HRR
M: Malate (L-Malic acid, C4H605); Sigma M 1000, 100 g, store at R.T.; FW = 134.1
Preparation of 400 mM stock solution (dissolved in H2O):
- 1) Weigh 268.2 mg of L-malic acid.
- 2) Add 3 ml H2O.
- 3) Neutralize with 10 N KOH (approx. 350 µl).
- 4) Adjust final volume to 5 ml (in 5 ml volumetric glass flask).
- 5) Divide into 0.5 ml portions.
- 6) Store frozen at -20 °C.
Comment: 800 mM stock until 2013-11-20.
Oxygraph-2k manual titrations: MiPNet09.12 O2k-Titrations
- Titration volume: 2.5 µl using a 25 µl Hamilton syringe.
- Final conc. in 2 ml O2k-chamber: 0.5 mM.
Malate: 0.5 mM versus 2 mM in HRR
In mitochondrial preparations obtained from a diversity of tissues and organisms malate at concentrations >0.5 mM exerted an inhibitory effect on CII linked and CI+II linked respiration, whereas 0.5 mM malate was saturating for CI linked respiration. Therefore, we recommend to use malate at a concentration of 0.5 mM in SUIT protocols.
- >> Further details: Discussion.
