Phosphate in yeast

B. Beauvoit, M. Rigonlet, B. Guerin, and P. Canioni (1989). Polyphosphates as a source of high energy phosphates in yeast mitochondria a P-NMR study. FEBS Lett., 252, 17-22. 

The mechanism of action of the coenzymes was discovered by Warburg and his co-workers in 1935. They studied the oxidation of glucose-6-phosphate in yeast extracts. This oxidation is caused by the combination of two enzymes, glucose-6-phosphate dehydrogenase (Zwischenferment) and the old yellow enzyme. 

In the biosynthesis of the thia2ole, cysteine is the common sulfur donor. In yeasts, the C-2 and N may be suppHed by glycine, and the remaining carbons byD-ribulose-5-phosphate [108321-99-9] (50). In anaerobic bacteria, the C-2 andN maybe recmited from tyrosine and the carbons from D-l-deoxyxylulose [16709-34-5] (51), whereas in aerobic bacteria the C-2 and N maybe derived from glycine, as in yeasts 7 (74—76,83—86) (see Fig. 9). 

Biosynthesis of pyrophosphate (5) from pyrimidine phosphate (47) and thia2ole phosphate (48) depends on the activity of five en2ymes, four of them kinases (87). In yeasts and many other organisms, including humans, pyrophosphate (5) can be obtained from exogenous thiamine in a single step cataly2ed by thiamine pyrophosphokinase (88). 

Recently another signal, the phenylalanine-tryptophan motif (or the motif containing two aromatic residues, such as (F/Y)X(F/Y), in yeast), was shown to direct some proteins including cation-dependent mannose 6-phosphate receptor (see Section IIIJ,2) from endosomes to the TGN (Schweizer et al., 1997 Burd et al., 1998). Most probably, it is used for the (retrograde) recycling processes. A putative coat complex was also discovered and named retromer (Seaman et al., 1998). 

Zhou, J. and Saba, J., 1998, Identification of the first mammalian sphingosine phosphate lyase gene and its fimctional expression in yeast, Biochim. Biophys. Res. Comm. 242 502-507. 

The long-known stimulating effect of mono- and polynitro com-pounds on the onset of fermentation in yeast maceration juice has been reinvestigated by Vandendriessche. The induction time is shortened significantly by 2,4- or 2,5-dinitrophenol, while 2,6-dinitro-phenol did not show such an effect. The influence is evident when using as substrates the fermentable hexoses and D-fructose-6-phosphate, but not hexose diphosphate. According to MarkoviCev a stimulation of the oxidation processes can be proved thereby. It is probable that these effects are related to the known phytochemical reduction of nitro compounds (see pp. 98 and 99). 

Vitamin Bg (8.47, pyridoxine) is a pyridine-alcohol, but its biologically active forms are pyridoxal 5-phosphate and the corresponding pyridoxamine. Like all the members of the vitamin B complex, it occurs in yeast, bran, wheat germ, and liver. It is a coenzyme of... 

The pyrophosphorylase of uridine 5 -(a-D-glucopyranosyl pyrophosphate), first detected in yeast,205 is widely distributed in Nature, and purified preparations of the enzyme have been obtained. With such a preparation from mammary gland, the phosphate 8 gave uridine 5 -(a-D-glucopyranosyl pyrophosphate) in about 95% yield.206... 

Fermentation procedures for preparing uridine 5 -(2-acetamido-2-deoxy-a-D-glucopyranosyl pyrophosphate) have also been reported. One of them255 involves the cultivation of Helminthosporium sativum in the presence of 2-amino-2-deoxy-D-glucose and the antibiotic polyoxin the latter is an inhibitor of chitin biosynthesis. The other256 utilized the incubation of yeast cells with uridine 5 -phosphate in the presence of an excess of 2-amino-2-deoxy-D-glucose and inorganic phosphate.257... 

One kind of active transport, namely group translocation, occurs in bacteria (for reviews, see Refs. 218-223), and some workers consider that this also takes place in yeasts (see, for example, Refs. 224 and 225) by this means, uptake of a sugar is directly coupled to its phosphorylation, and the sugar is released into the cytoplasm as a phosphate. 

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