Culture Media Additives

Dimethylsulfoxide (DMSO) is a very polar organic compound that is useful in organic chemistry for solubilizing organic and inorganic compounds. DMSO is also used as a cryoprotectant for cell media, preventing the formation of ice crystals, which would otherwise damage cells. DMSO can be used in PCR reactions to inhibit the self-complementation of DNA or PCR primers and increase amplification, especially for DNA sequences, which have GC rich sequences.

Epibrassinolide is a plant steroid hormone of the brassinosteroid family. Its functions include protection from environmental stressors and altering the metabolism under a variety of conditions. Epibrassinolide has been shown to decrease toxicity and stimulate healthy plant growth in plants under stress.

Erythromycin is a macrolide antibiotic isolated from Streptomyces erythreus. It displays strong efficacy against gram-positive cocci and bacilli and some mycobacteria, mycoplasma, and spirochetes. In addition to its antimicrobial properties, erythromycin is a motilin receptor agonist that has been shown to inhibit respiratory glycoconjugate secretion in vitro. It has also been used to select for recombinant Lactococcus lactis MG1363 strains in microbiological applications.

Idebenone is a synthetic analog of ubiquinone (CoQ10). It scavenges free radicals and acts as an antioxidant. Idebenone differs from ubiquinone by having a shorter, less lipophilic tail and thus can function in multiple cellular environments. In contrast to ubiquinone, idebenone acts as a competitive inhibitor of complex I in the electron transport chain and is capable of facilitating cellular respiration that is independent of a functioning complex I. It can accept electrons from the glycerophosphate shuttle, NADH-quinone oxidoreductase, and complex II of the electron transport chain. Idebenone was originally developed to treat cognitive disorders such as Alzheimer’s disease, but was not found to be effective so other uses are being explored.

L-Arabinose is an arabinose isomer widely found in nature, while D-arabinose is less common. L-Arabinose is a constituent of many biopolymers that make up plant cell walls.

This monosaccharide is often used in cell culture media, serving as a bacterial carbon source, and can be used to distinguish between bacteria based on their fermentation abilities.

L-Arabinose, in the absence of glucose, induces transcription of the ara operon in E. coli that encodes L-arabinose catabolizing enzymes. It does this by binding to the AraC protein and activating the P_BAD promoter. The P_BAD promoter is used in plasmid vectors as a switch for protein expression that can be turned on by L-arabinose or turned off by addition of glucose.

L-Arabitol is the reduced alcohol form of L-arabinose. It is produced by some fungus from enzymatic reduction of L-arabinose. L-Arabitol is metabolized by a variety of different bacteria and fungus utilizing an arabitol dehydrogenase enzyme. Arabitol dehydrogenase genes have been introduced into plants to serve as a positive selection marker for transgenic cells. L-Arabitol has been shown to be an inducer of a hydrolytic xylanase enzyme used for catabolism of L-xylose in the saprophytic fungus Hypocrea jecorina.

L-Fucose is a six-carbon deoxy monosaccharide that is equivalent to 6-deoxy-L-galactose. L-Fucose is found on many N- and O-linked glycans present on the cell surface of a wide variety of organisms. The most well-known fucosylated glycans are the ABO blood group antigens. L-fucose present in gastrointestinal mucous represses virulence factor-encoding genes expressed by enterohemorrhagic E. coli. Mutations in the gene that encodes alpha-L-fucosidase can cause fucosidosis, leading to a buildup of fucose-containing compounds which cause cellular malfunction.

Homocysteine is a cysteine homolog,and only differs by having an additional methylene bridge. It is often used in vitro as a reference to measure L-homocysteine in plasma in order to diagnose homocystinuria. This genetic disorder causes the body to be unable to process certain amino acids.

Higher levels of homocysteine found in the body is due to having vitamin B6 or B12 deficiencies. Finding higher levels may indicate possible cardiovascular disease; however, reducing the levels of homocysteine in the body does not appear to remedy the situation.

Sorbose is a ketose belonging to the group of sugars known as monosaccharides. L-Sorbose is the configuration of the naturally-occurring sugar and has a sweetness equivalent to that of sucrose. L-Sorbose is often used as a starting reagent for the biosynthesis of ascorbic acid and forms a colorless, clear solution when dissolved in water.

Tryptophan is an essential amino acid in the human diet. Its functions as a serotonin precursor have increased interest in its ability to treat depression and epilepsy; however, there has been inconclusive evidence in clinical trials regarding its efficacy in humans. Safety has also been a concern.

It is widely used in molecular genetics as an auxotrophic genetic marker in yeast gene disruption experiments.

Magnesium sulfate, heptahydrate is a magnesium ion source. Magnesium plays an important role in cell muscle physiology, cardiovascular and muscular activity and nucleic acid structure. Magnesium also functions as a cofactor for restriction enzymes like EcoR I and EcoR V, as well as deoxyribonuclease (DNase).

Magnesium sulfate, heptahydrate can also be used in the protocol for the isolation of chromosomes or nucleic acids.

Myo-Inositol is a vitamin added to promote growth in plant cell culture media. It can also be used to differentiate organisms based on metabolic properties. Myo-inositol is a component of membrane phospholipids.

β-Nicotinamide adenine dinucleotide (NAD+) plays a major role in metabolism as a cofactor and mobile electron acceptor. NAD+ is a required oxidizing cosubstrate for many enzymes. It is reduced to NADH (Cat# N-035) which carries electrons to the electron transport chain for subsequent oxidative phorphorylation and ATP production. NAD+ is capable of donating ADP-ribose moieties to a protein, producing nicotinamide in the process. Sirtuin enzymes use NAD+ as a substrate to deacetylate proteins and direct activity between the nucleus and mitochondria. NAD+ is regenerated by fermentation and by oxidative phosphorylation.

Reduced β-nicotinamide adenine dinucleotide (NADH) plays a major role in metabolism as a cofactor in redox reactions and as a mobile electron carrier. NADH is a high energy compound that donates electrons to the electron transport chain to provide energy for ATP production by oxidative phosphorylation. NADH is a required oxidizing cosubstrate in fermentation, which regenerates NAD (Cat# N-030). NADH is fluorescent, which provides for a relatively simple way to detect NADH in biological samples. NADH is also used in enzyme cycling assays to detect relevant biological molecules in tissues.

Nalidixic acid is a naphthyridone antibiotic that is similar in structure and mechanism to quinolones and is effective against both gram-positive and gram-negative bacteria. It acts as a bacteriostatic in lower concentrations but can be bacteriocidal at higher concentrations. Nalidixic acid indirectly inhibits proteins synthesis by binding DNA and interfering with enzymes involved in DNA replication and transcription.

NDSB-201 is a protein specific additive that can be used to help solubilize and stabilize proteins at non-denaturing concentrations while preventing protein aggregation.

NDSB-201 is a member of a group of nondetergent sulfobetaines. These zwitterionic compounds can reduce aggregation and aid in refolding and renaturing of proteins found in bacterial expression systems and in inclusion bodies. Unlike detergents such as CHAPS, NDSBs are nondenaturing, even at higher concentrations and have been shown to increase the yield efficiency of membrane and nuclear proteins, among others.

Nicotinamide is a metabolized amide form of vitamin B3. It is an anti-cancer agent and inhibitor of PARP-1, which is responsible for repairing DNA damage caused by chemotherapy. Nicotinamide is converted to nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) for use in biological redox reactions. Additionally, nicotinamide is a nicotinamide phosphoribosyltransferase (NAMPT) substrate and anti-inflammatory agent.

Palatinose, also called isomaltulose, is a dissacharide isomer of sucrose, and a commercially used sugar substitute. Similarly, it is fully digestible and provides the same caloric value as sucrose (approximately 4 cal/g). Palatinose is produced enzymatically from sucrose via bacteria expressing the isomerase isomaltulose synthase.

Palatinose is a low-glycemic and low-insulinemic saccharide. This occurs because the α-1, 6 glycosidic bond between glucose and fructose is hydrolyzed much slower than the α-1-β-2 bond in sucrose. The low-insulinemic attributes of Palatinose supports improved fat oxidation during physical activity as opposed to high insulin levels in sucrose adsorption, which can hinder the use of lipids as an energy source.

Potassium iodide is an inorganic compound that has many biological and biochemical applications. Potassium iodide is used as a source of iodine in thyrotoxic situations. Potassium iodide is also used to isolate single-stranded DNA (ssDNA), inhibit active oxygen and to quench fluorescent substances. Additionally, it is used as a chaotropic agent a (at high concentrations) to dissolve a gel matrix and can be used in DNA recovery from gel slides by gel dissolution.