Serine synthesis and

Serine metabolism. The pathways and structures of serine synthesis and degradation are shown. The major pathway of synthesis is presented as well as two pathways for degradation. 

In addition, incomplete oxidation of polyols leads to production of higher valued chemicals, such as dihydroacetone, which is a valuable tanning agent, hydroxypyruvic acid, which is a flavor component and a possible starting material for DL-serine synthesis, and tartronic and mesoxalic acids, which are important intermediates for novel polymer and pharmaceutical synthesis. Therefore, research on cogeneration of electricity and higher valued chemicals from polyols... 

The first synthesis of enterobactin, a microbial chelator and transporter of environmental iron, was accomplished by the coupling of three protected L-serine units and macrocyclization by the double activation method. 

After their synthesis (translation), most proteins go through a maturation process, called post-translational modification that affects their activity. One common post-translational modification of proteins is phosphorylation. Two functional classes of enzymes mediate this reversible process protein kinases add phosphate groups to hydroxyl groups of serine, threonine and tyrosine in their substrate, while protein phosphatases remove phosphate groups. The phosphate-linking... 

Figure 6.1 Synthesis and metabolism of acetylcholine. Choline is acetylated by reacting with acetyl-CoA in the presence of choline acetyltransferase to form acetylcholine (1). The acetylcholine binds to the anionic site of cholinesterase and reacts with the hydroxy group of serine on the esteratic site of the enzyme (2). The cholinesterase thus becomes acetylated and choline splits off to be taken back into the nerve terminal for further ACh synthesis (3). The acetylated enzyme is then rapidly hydrolised back to its active state with the formation of acetic acid (4)...

Verleysdonk, S, Martin, H, Willker, W, Leibfritz, D and Hamprecht, B (1999) Rapid uptake and degradation of glycine by astroglial cells in culture synthesis and release of serine and lactate. Glia 27 239-248. 

M. Karabork and S. Serin, in Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry (Dekker), 32 (9), 1635 (2002). 

Lejczak, B., Kafarski, P., Soroka, M., and Mastalerz, P., Synthesis of the phos-phonic acid analog of serine, Synthesis, 577,1984. 

Figure 1. Synthetic pathway for PS and PE in mammalian cells. The major steps occuring in the synthesis and interconversion of PS and PE are shown. The PS synthases condense serine with a phosphatidyl moiety derived from PC and PE. The nascent PS can be converted to PE by decarboxylation. PE can also be formed by transfer of a phosphoethanolamine moiety from CDP-ethanolamine to diacylglycerol via the Kennedy pathway. The abbreviations used are PC, phosphatidylcholine PS, phosphatidylserine PE, phosphatidylethanolamine DG, diacylglycerol PSD, phosphatidylserine decarboxylase PSS, PS synthase.

In A. vinelandii, C-terminal cleavage occurs in crude extracts after restoration of nickel and requires hours rather than minutes, as is the case in vivo. It does not require de novo protein synthesis and surprisingly is not redox or O2 sensitive. Also, it is not inhibited by well-established inhibitors of metallo- or serine protease families (Menon and Robson 1994). 

These three compounds exert many similar effects in nucleotide metabolism of chicks and rats [167]. They cause an increase of the liver RNA content and of the nucleotide content of the acid-soluble fraction in chicks [168], as well as an increase in rate of turnover of these polynucleotide structures [169,170]. Further experiments in chicks indicate that orotic acid, vitamin B12 and methionine exert a certain action on the activity of liver deoxyribonuclease, but have no effect on ribonuclease. Their effect is believed to be on the biosynthetic process rather than on catabolism [171]. Both orotic acid and vitamin Bu increase the levels of dihydrofolate reductase (EC 1.5.1.4), formyltetrahydrofolate synthetase and serine hydroxymethyl transferase in the chicken liver when added in diet. It is believed that orotic acid may act directly on the enzymes involved in the synthesis and interconversion of one-carbon folic acid derivatives [172]. The protein incorporation of serine, but not of leucine or methionine, is increased in the presence of either orotic acid or vitamin B12 [173]. In addition, these two compounds also exert a similar effect on the increased formate incorporation into the RNA of liver cell fractions in chicks [174—176]. It is therefore postulated that there may be a common role of orotic acid and vitamin Bj2 at the level of the transcription process in m-RNA biosynthesis [174—176]. 

Gershoff, S. N., and Earagalla, E. F. (1959). Endogenous oxalate synthesis and glycine, serine, deoxypyridoxine interrelationships in vitamin B6-deficient rats. /. Biol. Chem. 234, 2391-2393. 

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