Folkers, Karl

Fan, Rulin, 41 Farina, Vittorio, 50 Ferrier, Robert J., 62 Fettes, Alec, 67 Fieser, Louis F., I Fleming, Ian, 37 Folkers, Karl, 6 Fry, James L., 71 Fuson, Reynold C., 1... 

Brink, Norman G., and Folkers, Karl, Some Afreets of Streptomycin and Other Streptomyces Antibiotics. X 145... 

This proposal supported, with an earlier prediction of Sir Robert Robinson, that cholesterol was a cyclization product of squalene, a 30-carbon polymer of isoprene units. In 1953, Robert Bums Woodward and Bloch postulated a cyclization scheme for squalene (fig. 20.2) that was later shown to be correct. In 1956, the unknown isoprenoid precursor was identified as mevalonic acid by Karl Folkers and others at Merck, Sharpe, and Dohme Laboratories. The discovery of mevalonate provided the missing link in the basic outline of cholesterol biosynthesis. Since that time, the sequence and the stereochemical course for the biosynthesis of cholesterol have been defined in detail. 

Concentrations of tyramine and histamine were similar that of angiotonin is estimated. The preparation, which contained active amine oxidase and no other oxidases, was supplied by Karl Folkers of Merck and Company. Data were obtained from C. C. Stock, to whom the author is indebted. 

Amine oxidase was supplied through the courtesy of Karl Folkers, Merck and Company. 

The chemical structure of the penicillins remained in doubt throughout the war years despite considerable efforts and much speculation by a group led by Karl Folkers at Merck, and the Oxford group comprising Robert Robinson, Chain, Abraham and others. One of the major problems was that the initial microanalysis had not revealed the presence of a sulfur atom, and it was not until penicillamine was revealed in 1943 as the major acid degradation products of all the known penicillins that realistic structures could be... 

The Preparation of Thiophenes and Tetrahydrothiophenes Donald E. Wolf and Karl Folkers... 

In 1948, American chemist Karl Folkers (1906-1997) and his research team discovered that they could measure... 

The first component of vitamin B6, pyridoxine, was first synthesized, also in 1938, by the Austrian-German chemist Richard Kuhn (1900-1967). Its chemical structure was determined a year later by American chemists Karl August Folkers (1906-1997) and S. A. Harris (dates not available) at the... 

Coenzyme Q is well defined as a crucial component of the oxidative phosphoiylation system in the mitochondria, where energy derived from the products of fatty acids and carbohydrates is converted into ATP to drive cellular machinery and biosynthetic processes (Figure 36.3). Coenzyme Q (also known as ubiquinone) was discovered by Fred Crane and his colleagues in 1957 in beef heart mitochondria. Karl Folkers and his associates elucidated its chemical structure in 1958. Coenzyme Q is composed of a homologous series of compounds differing in the length of the isoprene side chain, and coenzyme Qio, the homologue present in humans and several other species, has 10... 

In a joint program with Karl Folkers at the University of Texas in Austin, TX, we evaluated the changes in coenzyme Qio levels in blood and other tissues following infection with murine Friend leukemia vims. The data revealed a significant coenzyme Qio deficiency in blood and spleen (mitochondria) as the infection progressed. On day 20 after the iirfection, the coenzyme Qio was reduced to 36% in blood and to 62% in spleen mitochondria (spleen being a major immune... 

The German-American biochemist Fritz Albert Lipmann (1899-1986) had discovered Coenzyme A in 1948, while working at the Massachusetts General Hospital in Boston. In 1951, Lynen succeeded at the University of Munich in the isolation of acetyl- Coenzyme A, (acetyl-CoA, the activated form of acetic acid) from yeast cells. Karl Folkers at Merck Sharp Dohme recognised in 1956 mevalonic acid as a critical unit in the terpene biosynthesis, while Lynen documented its formation from three acetyl-CoA moieties and the further route to fatty acids and terpenoids. Recently, another non-mevalonate pathway to terpe-nes (Rohmer pathway) has been discovered, which is not present in humans. 

Karl August Folkers and biotin crystals in polarised light. 

US biochemist Karl Folkers (1906-97) isolates vitamin B,2 (cyanocobalamin). 

A. Harris and Karl Folkers, from cyanoacetamide and l-ethoxypenta-2,4-dione. Newer processes include the use of 4-methyloxazoles. 

To explore the potentialities of semisynthetic cephalosporins it became imperative to find a method for the production of 7-ACA from cephalosporin C in a yield much higher than that obtained by acid hydrolysis. We confidently expected that an enzyme would be found that would catalyze the removal of the 8-(D-a-aminoadipyl) side chain the same view was expressed by Dr. Karl Folkers and Dr. Denkewalter who visited us in Oxford in 1959. In any event, widespread searches for such... 

---