Glycine, from threonine

Probable pathways for the catabolism of threonine are shown in Fig. 3. The enzymatic formation of glycine from threonine was first reported by Braunstein and Vilenkina. It has been confirmed by Meltzer and Sprinson and in the laboratories of the writer. - ... 

Figure 4.4 Release of amino acids from cortical slices exposed to 50 mM K+. Measurements by HPEC and fluorescence detection after reaction of amino acids with o-phthalaldehyde 1, aspartate 2, glutamate 3, asparagine 4, serine 5, glutamine 6, histidine 7, homoserine (internal standard) 8, glycine 9, threonine 10, arginine 11, taurine 12, alanine 13, GABA 14, tyrosine. Glutamate concentration is almost 1 pmol/gl which represents a release rate of 30 pmol/min/mg tissue...

Condensation products of DHB (which usually is found also in the fermentation broth) with amino acids were reported, viz. with glycine ixom Bacillus subtilis (164) named subsequently itoic acid (282) with serine from Escherichia coli (261) and Klebsiella oxytoca (196) with threonine from Klebsiella oxytoca (196) and Rhizobium spp. (275, 327) with arginine from Pseudomonas stutzeri (62) with glycine and threonine from Rhizobium sp. (240) with threonine and lysine as well as with leucine and lysine from Azospirillum lipoferum (312, 320). In most cases the isolate (sometimes designated as being a siderophore) was hydrolyzed and the constituents were determined by paper chromatography. The relative amounts of the constituents, the chiralities of the amino acids and the molecular mass of the isolate have not been determined. Hence it is not known whether condensation products of the enterobactin type exist. 

Serine-Glycine Interconversion. Feeding experiments in animals showed the formation of glycine from serine and threonine. An interconveision of serine and glycine was indicated by microbial nutritional experiments and confirmed by isotope experiments with both microbial and animal preparations. The carboxyl and a-carbon of serine are converted to gly-... 

This gradient system has been adapted for the analysis of coastal tind interstitial waters where compounds derived from amino acid degradation such as P-alaavae, taurine or amino butyric acids may occur in addition to the standard amino acids given in Table 26-1. For less complex samples such as, e.g., hydrolysates the gradient run time may be abbreviated and a linear gradient employed. It should, however, be noted that under these conditions glycine and threonine are usually not separated. 

The formation of serine from glydne and formate implies the partid-pation of folic acid and pyridoxal, and this has been demonstrated by several experiments with bacteria. A number of observations has shown that the serine is derived from the glycolysis pathway and finally yields glycine. The glycine can be formed not only from serine but also from threonine with formation of acetate. 

Typical aminocarboxyhc acids, unsaturated fatty acids bound in hpids, sugars and some other food components are precursors of many important sensory-active carbonyl compounds. Amino acids produce aldehydes mainly as secondary products of alco-hohc or lactic acid fermentations and during thermal processes by Strecker degradation. Formaldehyde (methanal) is formed from glycine, acetaldehyde (ethanal) from alanine propanal and butanal arise from threonine (Figure 8.3), 2-methylpropanal from valine. 

Many pyrroles arise mainly as products of the MaiUard reaction of carbohydrates and prohne. Unsubstituted pyrrole and some alkylsubstituted pyrroles also result from pyrolysis of other amino acids. For example, pyrrole appears in the pyrolysate of glycine, serine, threonine or prohne, 1-methylpyrrole arises from hydrox-yproline, and 2-methylpyrrole and 3-ethyl-4-methylpyrrole are products of serine and threonine degradation. In general, pyrroles... 

M hydrochloric acid at 107°C for 18 hr. The hydrolysate contained tryptophan, valine, glycine, proline, threonine, aspartic acid, and histidine in the (nearest integer) ratio of 1 1 1 1 2 2 1. The amino-terminal residue of the flavin peptide was found to be aspartic acid by the subtractive Edman method, with glycine as the next residue. Hydrolysis of the flavin peptide with 6 M hydrochloric acid for 17 hr at 95°C gave a histidylflavin which was purified by thin layer chromatography. Histidine was liberated from this histidylflavin by incubation at 125°C in 6 M hydrochloric acid. 

Amino acids are the main components of proteins. Approximately twenty amino acids are common constituents of proteins (1) and are called protein amino acids, or primary protein amino acids because they are found in proteins as they emerge from the ribosome in the translation process of protein synthesis (2), or natural amino acids. In 1820 the simplest amino acid, glycine, was isolated from gelatin (3) the most recendy isolated, of nutritional importance, is L-threonine which was found (4) in 1935 to be a growth factor of rats. The history of the discoveries of the amino acids has been reviewed... 

Likely impurities are aZZo-threonine and glycine. Crystd from water by adding 4 volumes of EtOH. Dried and stored in a desiccator. 

Now, it is seen that polar groups dominate the molecular structure, resulting from hydroxyl groups from the two serine and threonine fragments in addition to the peptide bonds themselves. Only weak dispersive interactions will be contributed by glycine fragments (CH2 groups). 

It was straightforward to identify the spin systems of four valines, five threonines, four alanines, three glycines, two glutamates, and AMX type residues (Asp, Cys, Phe, Tyr, Trp, and Ser) of this protein from the COSY, RELAY, and NOESY spectra in D O solution. The RELAY spectrum was particularly useful in identification of Val, Ala, Thr, and Glu spin systems. 

In some cases, the amino acid pattern on a paper chromatogram is very similar to that found in diseases of the renal tubules, such as cystinosis, where there is a failure to reabsorb all amino acids from the glomerular filtrate and, in consequence, the urinary amino acid pattern resembles that of plasma (W6, W9). In other cases the aminoaciduria is less marked and the amino acids found in greatest excess are glycine, alanine, serine, threonine, and glutamine. In some cases no aminoaciduria has been detected. 

By means of a procedure described above, Hanson and Fittkau (HI) isolated seventeen different peptides from normal urine. One of them, not belonging to the main peptide fraction, consisted of glutamic acid, and phenylalanine with alanine as the third not definitely established component. The remaining peptides contained five to ten different amino acid residues and some unidentified ninhydrin-positive constituents. Four amino acids, i.e., glutamic acid, aspartic acid, glycine, and alanine, were found in the majority of the peptides analyzed. Twelve peptides contained lysine and eight valine. Less frequently encountered were serine, threonine, tyrosine, leucine, phenylalanine, proline, hydroxyproline, and a-aminobutyric acid (found only in two cases). The amino acid composi-... 

---