1.Propionic acidaemia presenting with pancytopaenia in infancy.
Sweetman L, Nyhan WL, Cravens J, Zomer Y, Plunket DC. J Inherit Metab Dis. 1980;2(3):65-9.
A 2-month-old infant presented with vomiting, lethargy and pancytopaenia. She was found to have propionic acidaemia, and the activity of propionyl-CoA carboxylase in cultured fibroblasts was defective (McKusick 23200). Abnormal amounts of glycine, 3-hydroxypropionate, methylcitrate, tiglyglycine, propionylglycine, 2-methylacetoacetate, 2-methyl-3-hydroxybutyrate, 3-oxovalerate and 3-hydroxyvalerate were found in body fluids. It appears that the organic acidaemia leads to an inhibition in the maturation of cells in the bone marrow.
2.The influence of process parameters on the characteristics of polyhydroxyalkanoates produced by mixed cultures.
Serafim LS1, Lemos PC, Torres C, Reis MA, Ramos AM. Macromol Biosci. 2008 Apr 9;8(4):355-66.
The characterization of polyhydroxyalkanoates (PHA) produced by mixed cultures is fundamental for foreseeing the possible final applications of the polymer. In this study PHA produced under aerobic dynamic feeding (ADF) conditions are characterized. The PHA produced shows a stable average molecular weight ([symbol: see text]) in the range (1.0-3.0) x 10(6), along three years of reactor operation. Attempts to improve the amount of PHA produced did not introduce significant variations on the values [symbol: see text]. Along this period, the polydispersity indices (PDI) were between 1.3 and 2.2. The use of different carbon sources allowed the tailoring of polymer composition: homopolymers of poly(3-hydroxybutyrate), P(3HB), were obtained with acetate and butyrate, whereas a mixture of acetate and propionate, and propionate and valerate, gave terpolymers of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), and 2-methyl-3-hydroxyvalerate (2M3HV).
3.Adaptation of Cupriavidus necator to conditions favoring polyhydroxyalkanoate production.
Cavalheiro JM1, de Almeida MC, da Fonseca MM, de Carvalho CC. J Biotechnol. 2012 Dec 15;164(2):309-17. doi: 10.1016/j.jbiotec.2013.01.009. Epub 2013 Feb 1.
The fatty acid (FA) composition of the bacterial membrane of Cupriavidus necator DSM 545 was assessed during the time course of two-stage fed-batch cultivations for the production of short-chain polyhydroxyalkanoates (PHA). Changes in the relative proportion of straight, methyl and cyclopropyl saturated, unsaturated, hydroxy substituted and polyunsaturated FA were observed, depending on the C sources and cultivation conditions used to favor the synthesis of poly(3-hydroxybutyrate) (P(3HB)), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) or poly(3-hydroxybutyrate-4-hydroxybutyrate-3-hydroxyvalerate) (P(3HB-4HB-3HV)), under N limiting conditions. The relative percentage of each FA class was studied using glucose or waste glycerol (GRP), as main C source for P(3HB) production. The FA profile was also assessed when GRP was used together with i) γ-butyrolactone (GBL) (precursor of 4HB monomers) for P(3HB-4HB) synthesis and ii) GBL and propionic acid (PA) (3HV precursor) to yield P(3HB-4HB-3HV).
4.Preparation of single-enantiomer 2-methyl-4-heptanol, a pheromone of Metamasius hemipterus, using (S)-2-methoxy-2-(1-naphthyl)propionic acid.
Ichikawa A1, Ono H. J Chromatogr A. 2006 Jun 2;1117(1):38-46. Epub 2006 Apr 24.
To investigate the resolution of secondary alcohols using 2-methoxy-2-(1-naphthyl)propionic acid (MalphaNP acid), 2-methyl-4-heptanol, one of the aggregation pheromones of Metamasius hemipterus, was resolved using (S)-MalphaNP acid. As a chiral-resolving agent, MalphaNP acid is superior to 3,3,3-trifluoro-2-methoxy-2-phenylpropionic acid (MTPA) in terms of HPLC separation and NMR shielding. A better separation of diastereomeric MalphaNP esters was observed when n-hexane-THF was used as the eluent for silica gel HPLC. The solvolysis of the diastereomeric MalphaNP esters gave (R)-2-methyl-4-heptanol and its enantiomer; enantiopure (S)-MalphaNP acid was also recovered. In addition, the preferred conformation of the MalphaNP ester was confirmed using methyl (R)-3-hydroxyvalerate as an authentic compound.