Enzymatic conversion of N carbamoyl-d-amino acids to d-amino acids

An enzyme isolated from Agrobacterium radiobacter was shown to catalyse the following reaction: $\text{H}{}_2\text{O}\text{+ N-}\text{carbamoyl-}\text{d}\text{-amino acid}\text{→}\text{d}\text{-amino acid}\text{+}\text{NH}{}_3\text{+}\text{CO}{}_2$ Some properties of this new enzyme, $\text{N-}\text{carbamoyl-}\text{d}\text{-amino}$ acid amidohydrolase, are presented in this paper. The potential application of this enzyme for the preparation of some d-amino acids used as pharmaceutical intermediates is discussed.     

Microbial desulfonation of substituted naphthalenesulfonic acids and benzenesulfonic acids

Sulfur-limited batch enrichment cultures containing one of nine multisubstituted naphthalenesulfonates and an inoculum from sewage yielded several taxa of bacteria which could quantitatively utilize 19 sulfonated aromatic compounds as the sole sulfur source for growth. Growth yields were about 4 kg of protein per mol of sulfur. Specific degradation rates were about 4 to 14 mu kat/kg of protein. A Pseudomonas sp., an Arthrobacter sp., and an unidentified bacterium were examined. Each desulfonated at least 16 aromatic compounds, none of which served as a carbon source. Pseudomonas sp. strain S-313 converted 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 5-amino-1-naphthalenesulfonic acid, benzenesulfonic acid, and 3-aminobenzenesulfonic acid to 1-naphthol, 2-naphthol, 5-amino-1-naphthol, phenol, and 3-aminophenol, respectively. Experiments with 18O2 showed that the hydroxyl group was derived from molecular oxygen.     

Intermediates in the metabolism of m-carboxy-substituted aromatic amino acids in plants: Phenylpyruvic acids,mandelic acids,and phenylglyoxylic acids

Tracer experiments with ¹⁴C-labelled precursors in Iris × hollandica cv. Wedgwood, Roseda lutea L. and Reseda Odorata L. have demonstrated that 3-(3-carboxyphenyl)alanine and 3-(3-carboxy-4-hydroxyphenyl)alanine can be derived from the corresponding pyruvic acids, presumably by unspecific trans-aminations, and that (3-carboxyphenyl)glycine and (3-carboxy-4-hydroxy-phenyl)glycine can be derived from the corresponding phenylglyoxylic acids The glycine derivatives are derived from the alanine derivatives, and the corresponding mandelic acids are intermediates in these transformations. The corresponding phenylacetic acids are incorporated only slightly into the glycine derivatives, indicating that oxidation at the benzylic position in the C₆–C₃ compounds takes place early in the transformation. The corresponding cinnamics acids are not metabolized at all in the plants.     

Microbial desulfonation of substituted naphthalenesulfonic acids and benzenesulfonic acids.

Sulfur-limited batch enrichment cultures containing one of nine multisubstituted naphthalenesulfonates and an inoculum from sewage yielded several taxa of bacteria which could quantitatively utilize 19 sulfonated aromatic compounds as the sole sulfur source for growth. Growth yields were about 4 kg of protein per mol of sulfur. Specific degradation rates were about 4 to 14 mu kat/kg of protein. A Pseudomonas sp., an Arthrobacter sp., and an unidentified bacterium were examined. Each desulfonated at least 16 aromatic compounds, none of which served as a carbon source. Pseudomonas sp. strain S-313 converted 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 5-amino-1-naphthalenesulfonic acid, benzenesulfonic acid, and 3-aminobenzenesulfonic acid to 1-naphthol, 2-naphthol, 5-amino-1-naphthol, phenol, and 3-aminophenol, respectively. Experiments with 18O2 showed that the hydroxyl group was derived from molecular oxygen.     

Transformation of some hydroxy amino acids to other amino acids

It has been observed that -hydroxy--amino acids are transformed into other amino acids, when heated in dilute solutions with phosphorous acid, phosphoric acid or their ammonium salts. It has been shown that as in the case of previously reported glycine-aldehyde reactions, glycine also reacts with acetone to give -hydroxyvaline under prebiologically feasible conditions. It is suggested, therefore, that the formation of -hydroxy--amino acids and their transformation to other amino acids may have been a pathway for the synthesis of amino acids under primitive earth conditions.     

Candida cloacae oxidation of long-chain fatty acids to dioic acids

Candida cloacae cells oxidize long-chain fatty acids to their corresponding dicarboxylic acids (dioic acids) at rates dependent on their chain length and degree of saturation. This is despite the well-known toxicity of the fatty acids. Among the saturated substrates, the oxidation is limited to lauric acid (C12). The addition of pristane (5% v/v), which acts as an inert carrier for the poorly water-soluble substrate, boosts the oxidation of lauric acid to a rate that is comparable to that of dodecane. When dissolved in pristane, myristic (C14) and palmitic (C16) acids are effective carbon sources for C. cloacae, but dioic acid production is very low. Media glucose concentration and pH also influence cell growth and productivity. After the glucose is depleted, oxidation is optimal at a low pH. A two-phase (pristane/water) reaction was tested in a 2-l stirred tank bioreactor in which growth and oxidation were separated. A 50% w/w conversion of lauric acid (10 g/l) to dodecanedioic acid was achieved. The bioreactor also alleviated poor mass transfer characteristics experienced in shake flasks.     

Anticonvulsant activity of benzylamides of some amino acids and heterocyclic acids

A series of new potential anticonvulsants have been synthesized. They are N-methyl benzyl-amides of N-methyl Asp and N-methyl Glu (R and S), benzylamides of some heterocyclic acids and their N-oxides and benzylamides of two heteroalicyclic acids. The obtained compounds were evaluated in the Anticonvulsant Screening Project (ASP) of Antiepileptic Drug Development Program (ADDP) of NIH.     

Polysialic acids

• 1.1. Polysialic acids are linear homopolymers of N-acetylneuraminic acid (Neu5Ac), N-glycolylneuraminic acid (Neu5Gc) and deaminated neuraminic acid (KDN) residues joined by α 2,8, α 2–9 or α2,8/α2,9 ketosidic linkages.
• 2.2. They occur in glycoproteins of embryonic neural membranes (playing a role of neural cell adhesion molecules), in non-neural tissues (postnatal kidney), tumours, (neuroectodermal tumours), fish eggs and in the capsule of certain bacteria such as Neisseria meningitidis group B.
• 3.3. These polymers are synthesized through reactions which involve (a) the synthesis of sialic acid; (b) its activation to a cytidine monophosphate sugar nucleotide and (c) the polymerization of the different residues by a polysialyl-transferase complex.
• 4.4. Polysialic acids are involved in organogenesis and in cell growth. In several tissues they act as oneodevelopmental antigens, and in bacteria are also virulent determinants.