Embden—Meyerhof pathway

Metabolic Functions. The formation of phosphate esters is the essential initial process in carbohydrate metaboHsm (see Carbohydrates). The glycolytic, ie, anaerobic or Embden-Meyerhof pathway comprises a series of nine such esters. The phosphogluconate pathway, starting with glucose, comprises a succession of 12 phosphate esters. 

Yeast (qv) metabolize maltose and glucose sugars via the Embden-Meyerhof pathway to pymvate, and via acetaldehyde to ethanol. AH distiUers yeast strains can be expected to produce 6% (v/v) ethanol from a mash containing 11% (w/v) starch. Ethanol concentration up to 18% can be tolerated by some yeasts. Secondary products (congeners) arise during fermentation and are retained in the distiUation of whiskey. These include aldehydes, esters, and higher alcohols (fusel oHs). NaturaHy occurring lactic acid bacteria may simultaneously ferment within the mash and contribute to the whiskey flavor profile. 

All overview of the glycolytic pathway is presented in Figure 19.1. Most of the details of this pathway (the first metabolic pathway to be elucidated) were worked out in the first half of the 20th century by the German biochemists Otto Warburg, G. Embden, and O. Meyerhof. In fact, the sequence of reactions in Figure 19.1 is often referred to as the Embden-Meyerhof pathway. 

Embden-Meyerhof pathway (Section 29.5) An alternative name for glycolysis. 

Elimination reaction, 138. 383-393 biological examples of, 393 summary of, 393-394 Embden-Meyerhof pathway, 1143-1150 see also Glycolysis... 

Defects in the Embden-Meyerhof Pathway 3.2.1. Hexokinase Deficiency... 

For many years, it was considered that the Embden-Meyerhof pathway was the major route of carbohydrate metabolism in a wide variety of organisms. However, evidence has been slowly accumulated to suggest that alternative routes exist. 

It is difficult to realize that there were still unknown reactions in the glycolytic (Embden-Meyerhof) pathway until World War II. One of the then standard biochemistry texts (Thorpe) summarized the position in the 1938 edition as ... 

You will probably be familiar with glycolysis (the Embden-Meyerhof pathway, Figure 1.20) from previous studies at school perhaps, so let s use this important pathway to illustrate some points in the recommended strategy. 

One approach to compartmentalize hemoglobin is to encapsulate hemoglobin in biodegradable polymer-PEG-polylactide (30). These nanocapsules have a diameter of 80-150 nm and contain superoxide dismutase, catalase, carbonic anhydrase, and other enzymes of Embden-Meyerhof pathway that are needed for long-term function of an oxygen carrier (31,32). The polylactide capsules are metabolized in vivo to water and carbon... 

With the advent of PM3, biochemical reactions, for example, those involved in the Embden—Meyerhof pathway, can be studied. Until now, systems such as glucose-6—phosphate were either poorly represented, or were prohibitively slow to calculate. 

The glycolytic pathway was the first major metabolic sequence to be elucidated. Much of the definitive work was done in the 1930s by the German biochemists, Gustav Embden, Otto Meyerhof, and Otto Warburg. Because of their contributions the alternative name, Embden-Meyerhof pathway, is sometimes used for the glycolytic pathway. 

An alternative pathway to the Embden-Meyerhof pathway of glycolysis for conversion of carbohydrates to pyruvate is the pentose-phosphate pathway (Fig. 5.13). Its main role is not ATP production but to provide NADPH for fat synthesis, and pentoses (in particular, D-ribose-5-phosphate) for nucleic acid synthesis. The pathway can also convert pentoses to hexoses, which can then be further metabolised by glycolysis. With regard to cestodes, a... 

Schroder, C., Selig, M., and Schonheit, P. 1994. Glucose fermentation to acetate, C02 and H2 in the anaerobic hyperthermophilic eubacterium Thermotoga maritima involvement of the Embden-Meyerhof pathway. Arch. Microbiol., 767,460-470. 

The action of ammonia on cytidine ribitol pyrophosphate (III) gave a cyclic phosphate IX which was oxidized by periodate and bromine to yield X, the cyclic 2,3-0-phosphate of glyceronic acid. This substance was purified by paper chromatography, and hydrolyzed with acid to the 2-phos-phate (XI) and 3-phosphate (XII) of D-glyceronic acid. These substances were utilized by a multi-enzyme system from rabbit muscle which degrades carbohydrates by way of the Embden-Meyerhof pathway. The ribitol phosphate (VII) is therefore L-ribitol 1-phosphate (o-ribitol 5-phosphate). ... 

Two metabolic patterns are discernible from the results. Carbon atoms 2, 1, and 7 of shikimate (VI) are derived almost equally from G-1,6, G-2,5, and G-3,4, respectively. In the Embden-Meyerhof pathway of hexose metabolism (see Fig. 2), D-fructose 1,6-diphosphate is cleaved to 1,3-dihydroxy-2-propanone phosphate (G-1,2,3) and D-glycerose 3-phosphate (G-4,5,6), and the two trioses are interconverted by triose phosphate isomerase. The observed randomization of label between Cl and C6, C2 and C5, and C3 and C4 of hexose therefore implies that C2, Cl, and C7 of shikimate are derived from a 3-carbon intermediate of glycolysis. The small but significant preponderance of G-6 over G-1, of G-5 over G-2, and, presumably, of G-4 over G-3, can be explained by recent observations that, in the aldolase cleavage of D-fructose 1,6-diphosphate, the 1,3-dihy-... 

Fig. 2.—a Schematic Representation of the Embden-Meyerhof Pathway to Show the Distribution of Label from n-Glucose in the 3-Carbon Intermediates of the Pathway. [P denotes —PO(OH)j.]... 

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