Glycine serine formation

Signal sequences vary in structure but usually have a net positive charge within the first 5-8 residues at the N terminus. This region is followed by a "hydro-phobic core" made up of 8-10 residues with a strong tendency toward a helix formation. This sequence is often followed by one or a few proline, glycine, or serine residues and then a sequence AXA that immediately precedes the cleavage site. Here, A is usually alanine in prokaryotes but may also be glycine, serine, or threonine in eukaryotes. Residue X is any amino... 

Previous studies have reported silver staining with other amino acids. Heukeshoven and Dernick reported silver staining of the homopolymers of glycine, serine, proline and aspartic acid (4 ) while Nielsen and Brown reported the formation of colored silver complexes with aspartate, and tyrosine (45,). Staining of these homopolymers was not observed in the study of Merril and Pratt (32,), and prior metal binding studies failed to demonstrate metal interactions with the side-chain hydroxyl groups of serine, threonine or tyrosine... 

Application of this inhibitor to pea leaves (Miflin et al., 1966) caused glycine, but not glycolate to accumulate. Also, addition of nonradioactive glyoxylate with radioactive glycine stimulated rather than inhibited radioactive serine formation. It was suggested by Miflin et al. (1966), therefore that serine was formed from two molecules of glycine by a mechanism similar to that already known in bacteria and in avian liver [Eq. (4)]. 

Polymerization of the A -carboxyanhydrides of the l isomers of alanine, leucine, lysine, glutamic acid, phenyl alanine, and methionine leads to the a form, but those of the L-forms of cysteine, glycine, serine and valine yield the form. Processing requires the soluble a form, and this eliminates commercial use of the last named amino acids. Spinning must be carried out at concentrations low enough to prevent formation of mesophases. The a forms... 

Most research on the effect of folate deficiency on lymphoid cell metabolism has focused on the enzymes involved in pyrimidine synthesis. Defective interconversion of glycine and serine has been reported in peripheral lymphocytes from folate deficient patients due to folate malabsorption, malnutrition or treatment with phenytoin (Ellegaard and Esmann, 1972), methotrexate, (Ellegaard and Esmann, 1973). In fact estimation of serine formation in lymphocytes cultured with glycine and labeled formate is the basis for the test developed to detect early folate deficiency before the appearance of megaloblastic changes in the bone marrow and low RBC folate levels (Ellegaard and Esmann, 1973). 

For many serine and cysteine peptidases catalysis first involves formation of a complex known as an acyl intermediate. An essential residue is required to stabilize this intermediate by helping to form the oxyanion hole. In cathepsin B a glutamine performs this role and sometimes a catalytic tetrad (Gin, Cys, His, Asn) is referred too. In chymotrypsin, a glycine is essential for stabilizing the oxyanion hole. 

Despite our earlier failure in formate feeding experiments, [3- C]serine, [1,2- CJglycine, and [Me- C]methionine were found to enrich C-13 in neosaxitoxin effectively (7). The best incorporation was observed with methionine, indicating it is the direct precursor via S-adenosylmethionine. Glycine C-2 and serine C-3 must have been incorporated through tetrahydrofolate system as methyl donors in methionine biosynthesis. 

Selectivity studies with DTU indicated marked discrimination in the clathrate formation 23,45). As in other types of clathrates, the steric factor is important in differentiation between compounds of similar functionality but different shape. For example, DTU forms crystalline complexes with some alcohols (methanol, ethanol, propanol, 1-butanol) but not with others (2-butanol). It complexes the ethyl esters of N-acetyl derivatives of glycine, alanine, methionine and aspartic acid, but not of proline, serine, phenylalanine and glutamic acid. 

Connections One-carbon fragments in from serine, glycine, formate, and histidine... 

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