Acetate replacing factor

The isolation of lipoic acid in 1951 followed an earlier discovery that the ciliate protozoan Tetrahymena geleii required an unknown factor for growth. In independent experiments acetic acid was observed to promote rapid growth of Lactobacillus casei, but it could be replaced by an unknown "acetate replacing factor." Another lactic acid bacterium Streptococcus faecalis was unable to oxidize pyruvate without addition of "pyruvate oxidation factor." By 1949, all three unknown substances were recognized as identical.291 2913 After working up the equivalent of 10 tons of water-soluble residue from liver, Lester Reed and his collaborators isolated 30 mg of a fat-soluble acidic material which was named lipoic acid (or 6-thioctic acid).292 294... 

Common Name Acetate replacing factor Acidum lipoicum Acidum... 

Lipoic Acid. The formation of acetyl CoA from pyruvate involves an additional cofactor, lipoic acid. This compound was studied independently as a growth factor for the protozoa Tetrahymena (protogen), a growth factor for Lactobacillus casei (acetate replacing factor) and a pyruvate oxidation factor for Streptococcus faecalis. - Pure synthetic compounds were made and called thioctic acid and lipoic acid. The officially accepted name for the structure given below is lipoic acid. Lipoic acid is... 

Study of the mechanism of the oxidation of pyruvic acid by certain bacteria led to the discovery of lipoic acid (thioctic acid) as a nutrient metabolite essential for the oxidative decarboxylation of a-keto acids. It subsequently was determined that the acetate-replacing factor " for lactic acid bacteria and protogen,a growth factor for the protozoan, Tetrahymena gelii, were also identical with lipoic acid. The occurrence of considerable quantities of lipoic acid in mammalian preparations of pyruvate and a-ketoglutarate oxidases suggests that it has the same function in animal tissues as in microorganisms. ... 

The blocked-out purification of pyruvate oxidation factor was taken with us to Indiana and the early steps were scaled up for us at the Eli Lilly Research Laboratories in Indianapolis. Later, at the time of my transfer to Illinois, a realignment of the LUly research mana ment revealed to them the identity of the pyruvate oxidation and the acetate replacing factors, the latter supplied to Lester Reed at Texas. A pointed encouragement came from Lilly for us to join forces, which we did, continuing with the best features from each effort. ... 

Mevalonic acid as specific precursor of isoprenoids Since the discovery of mevalonic acid (MVA) isolated from distillates of brewers yeast as an acetate-replacing growth factor in the culture broth of Lactobacillus acidophilus [3], and especially its excellent incorporation into cholesterol in rat liver homogenates [4,5], speculations on the "true" comitted precursor molecule for isoprenoid biosynthesis were practically terminated. By monitoring the incorporation of labeled MVA into... 

Chromatography by ion exchange on a sulfonated poly(styrene-co-divinyl benzene) phase has been proposed as a replacement for titrimetry.57 Eluted by a dilute solution of a neutral salt such as sodium ethanesulfonate, the conductance of the protons can be measured in the absence of a suppressor from sub-millimolar to molar concentration. The response factors of mono-, di-, and trichloroacetic acid and of o-phthalic acid were large and essentially equivalent to ethanesulfonic acid, while the response factor of acetic acid was far smaller. A syringe pump has generated pressures as high as 72,000 psi (5000 bar) in a capillary column packed with 1 p particles, generating a fraction capacity of 300 peaks in 30 minutes.58... 

In contrast to the effect of manganese, cupric salt strongly retards the oxidation, reducing the rate of p-xylene by a factor of more than 10 when 20% of cobalt is replaced by cupric acetate. 

Acetic acid is a stronger acid than ethanol by a factor of about 10. In both compounds the acidic hydrogen is bonded to an oxygen. Replacing the CH2 of ethanol with a C=0 results in an enormous increase in acidity. Part of this increase is due to the inductive effect of the oxygen of the carbonyl group, but the effect is much too large to be due only to this. 

Electrophilic hydrogen exchange in deuterioselenophenes was studied using a 4 1 mixture of acetic and trifluoroacetic acids.79 Rate constants and partial rate factors were determined for the deuterium replacement at 25°C (see Table IV). Rate constants were calculated... 

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