(S)-Malic acid ((S)-2-Hydroxysuccinic acid) is a naturally occurring dicarboxylic acid, a source of sweet and sour fruit, and is widely used as a food additive.

Physicochemical Properties

Molecular Formula	C4H6O5
Molecular Weight	134.0874
Exact Mass	134.021
Elemental Analysis	C, 35.83; H, 4.51; O, 59.66
CAS #	97-67-6
Related CAS #	26999-59-7
PubChem CID	222656
Appearance	White to off-white solid powder
Density	1.6±0.1 g/cm3
Boiling Point	306.4±27.0 °C at 760 mmHg
Melting Point	101-103 °C(lit.)
Flash Point	153.4±20.2 °C
Vapour Pressure	0.0±1.5 mmHg at 25°C
Index of Refraction	1.529
LogP	-1.26
Hydrogen Bond Donor Count	3
Hydrogen Bond Acceptor Count	5
Rotatable Bond Count	3
Heavy Atom Count	9
Complexity	129
Defined Atom Stereocenter Count	1
SMILES	C([C@@H](C(=O)O)O)C(=O)O
InChi Key	BJEPYKJPYRNKOW-REOHCLBHSA-N
InChi Code	InChI=1S/C4H6O5/c5-2(4(8)9)1-3(6)7/h2,5H,1H2,(H,6,7)(H,8,9)/t2-/m0/s1
Chemical Name	(2S)-2-hydroxybutanedioic acid
Synonyms	97-67-6; L-Malic acid; L-(-)-Malic acid; (S)-2-hydroxysuccinic acid; (2S)-2-Hydroxybutanedioic acid; (S)-Malic acid; L(-)-Malic acid; (-)-Malic acid;
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

Targets	Endogenous Metabolite
ln Vitro	It has been demonstrated that ME is required for (S)-2-Hydroxysuccinic acid (L-malic acid) consumption in L. casei. Furthermore, deleting either the gene encoding the histidine kinase or the response regulator of the TC system resulted in the loss of the capacity to grow on (S)-2-Hydroxysuccinic acid, demonstrating that the homologous TC system regulates and is required for ME expression. MaeE expression is induced in the presence of (S)-2-Hydroxysuccinic acid and repressed by glucose, whereas TC system expression is induced by (S)-2-Hydroxysuccinic acid but not repressed by glucose[1].
Enzyme Assay	Lactobacillus casei can metabolize L-malic acid via malolactic enzyme (malolactic fermentation [MLF]) or malic enzyme (ME). Whereas utilization of L-malic acid via MLF does not support growth, the ME pathway enables L. casei to grow on L-malic acid. In this work, we have identified in the genomes of L. casei strains BL23 and ATCC 334 a cluster consisting of two diverging operons, maePE and maeKR, encoding a putative malate transporter (maeP), an ME (maeE), and a two-component (TC) system belonging to the citrate family (maeK and maeR). Homologous clusters were identified in Enterococcus faecalis, Streptococcus agalactiae, Streptococcus pyogenes, and Streptococcus uberis. Our results show that ME is essential for L-malic acid utilization in L. casei. Furthermore, deletion of either the gene encoding the histidine kinase or the response regulator of the TC system resulted in the loss of the ability to grow on L-malic acid, thus indicating that the cognate TC system regulates and is essential for the expression of ME. Transcriptional analyses showed that expression of maeE is induced in the presence of L-malic acid and repressed by glucose, whereas TC system expression was induced by L-malic acid and was not repressed by glucose. DNase I footprinting analysis showed that MaeR binds specifically to a set of direct repeats [5'-TTATT(A/T)AA-3'] in the mae promoter region. The location of the repeats strongly suggests that MaeR activates the expression of the diverging operons maePE and maeKR where the first one is also subjected to carbon catabolite repression[1].
References	[1]. Requirement of the Lactobacillus casei MaeKR two-component system for L-malic acid utilization via a malic enzyme pathway. Appl Environ Microbiol. 2010 Jan;76(1):84-95.
Additional Infomation	(S)-malic acid is an optically active form of malic acid having (S)-configuration. It has a role as a geroprotector. It is a conjugate acid of a (S)-malate(2-). It is an enantiomer of a (R)-malic acid. L-Malic acid is a metabolite found in or produced by Escherichia coli (strain K12, MG1655). (2S)-2-Hydroxybutanedioic acid has been reported in Rehmannia glutinosa, Punica granatum, and other organisms with data available.

Solubility Data

Solubility (In Vitro)

DMSO : ~100 mg/mL (~745.77 mM) H2O : ~100 mg/mL (~745.77 mM)

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.5 mg/mL (18.64 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.5 mg/mL (18.64 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Solubility in Formulation 3: ≥ 2.5 mg/mL (18.64 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	7.4577 mL	37.2884 mL	74.5768 mL
	5 mM	1.4915 mL	7.4577 mL	14.9154 mL
	10 mM	0.7458 mL	3.7288 mL	7.4577 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.