François Le Goffic

Purification and characterization of deep sea sharkCentrophorus squamosus liver oil 1-O-aklylglycerol ether lipids

The 1-O-alkylglycerol composition of the liver oil of the deep sea sharkCentrophorus squamosus, a species which provides edible flesh, has been determined. After various fractionations of the oil, the unsaponifiable fraction was characterized by means of gas chromatography/mass spectrometry, electron impact, and positive-ion chemical ionization. The oil is composed of 60% unsaponifiable matter, containing 45% squalene, 4.5% cholesterol, and 10% of linear saturated and monounsaturated glycerol ethers with 14–18 carbon atoms. After a first separtion by chromatography on silicic acid, monounsaturated glycerol ethers have been separated from the saturated homologues, in particular from 1-O-octadecylglycerol (batyl alcohol) and 1-O-hexadecylglycerol (chimyl alcohol)via urea complexation. This newer application of the urea method, already used in the past to extract saturated from polyunsaturated fatty acids, allowed the purification of the main components of the complex unsaturated glycerol ether fraction, namely, 1-O-octadecen-9′ylglycerol (selachyl alcohol) and 1-O-hexadecen-9′ylglycerol.

Synthesis of optically active β,γ-alkynylglycine derivatives☆

Abstract Full results on the first synthesis of optically active β,γ-alkynylglycine derivatives from naturally occurring L-serine are described. The methodology uses L-serinal as a key intermediate and allows great versatility in the introduction of N-protective groups and of alkyne substitution. The N-Boc protected β,γ-alkynylglycine derivatives described have ee greater than 90%.

Glucosamine-6-phosphate synthase from Escherichia coli yields two proteins upon limited proteolysis: Identification of the glutamine amidohydrolase and 2R ketose/aldose isomerase-bearing domains based on their biochemical properties

The proteolysis of native glucosamine-6-phosphate synthase (Mr 67,000) from Escherichia coli was investigated using two nonspecific and five specific endoproteinases, alpha-chymotrypsin generated two nonoverlapping polypeptides CT1 and CT2 of Mr 40,000 and 27,000 lacking glucosamine-6P synthesizing activity. Amino terminal and carboxy terminal sequence analysis showed that cleavage occurred between positions 240 and 241 of the primary sequence without further degradation. The glutamine amidohydrolase activity was located in the CT2 N-terminal polypeptide which was capable of incorporating 0.7 equivalent of the glutamine site-directed affinity label [2-3H]-N3-(4-methoxyfumaroyl)-diaminopropionic acid indicating that it bears the amidotransferase function. CT1 which displayed a higher reactivity than CT2 for fructose-6P binding contains the ketose/aldose isomerase activity. These data suggest the existence of a hinge structure essential for the catalytically efficient coupling between the ammonia generating domain and the sugar binding domain and support the model recently proposed by Mei and Zalkin in which purF-type amidotransferases contain a glutamine hydrolase domain of approximately 200 amino acids fused to an ammonia-transfer domain.

Chemoenzymatic approach to carbocyclic analogues of ribonucleosides and nicotinamide ribose.

Abstract Resolution of(±) methyl-4- cis -acetamido-cyclopent-2-ene carboxylate 1 was performed by enzymatic enantioselective hydrolysis using pig liver esterase with ee of 87 % and 97 %.

En route to optically active ethynylglycine derivatives

Abstract First results in the synthesis of chiral non racemic ethynylglycine derivatives from protected L-serinal are described.

Limits of wiped film short-path distiller

This paper presents the behavior of a binary system in a short-path distiller in the stationary region where there is no temperature change in the liquid flow. The model used is a wiped film one and the heat transfer is supposed to be sufficient to ensure the evaporation process. A relationship between the heating surface, the initial concentration, the overall throughput and the concentration change inside the distiller is established. The quality and quantity of the output flows are also deduced, as well as the limit of purification which can be obtained.

A new approach for using cofactor dependent enzymes: example of alcohol dehydrogenase

The use of enzymes requiring a cofactor as substrate in organic synthesis is still a problem since the cofactors are expensive. This study deals with a new approach consisting of using fragments of NAD+. Three fragments of NAD(H) are examined. The activities of NMN+ and NMNH are greatly improved by the addition of adenosine in ethanol oxidation and in cyclohexanone reduction, respectively. Nicotinamide monocucleoside is not active in the ethanol oxidation but the addition of AMP promotes this reaction.

A new and easy synthesis of 2-carboxy-6-oxo-cis-octahydroindole

Abstract The title compound has been synthetised by acidic fragmentation of the Diels-Alder adduct obtained by reacting 1-methoxy-1-cyclohexadiene on N-acetyl dehydroalanine methylester.

Synthesis and evaluation of inhibitors for Escherichia coli glucosamine-6-phosphate synthase

Abstract The design, synthesis and evaluation of potential affinity labels of Escherichia coli glucosamine-6-phosphate synthase (glmS) are described. Among the inhibitors described, 2-amino-3-(( N -halomethyl)amino)propanoates 1a and 2a and 2-amino-3-( N -maleimidyl)propanoate 4a exhibited time-dependent inhibition parameters similar to those previously obtained for N 3 -(4-methoxyfumaroyl)diaminopropanoate 5 , the most efficient synthetic inhibitor of glmS reported to date. From the recently elucidated mechanism of glmS inactivation by 5 , the alkylation of cysteine-1-thiol by 1a, 2a and 4a seems very likely.

Purification and separation of various plasmid forms by exclusion chromatography

A chromatographic method for the rapid isolation of preparative amounts of plasmid DNA without the use of cesium chloride centrifugation is described. The protocol uses the alkaline extraction procedure and an exclusion column of Fractogel TSK 75S. From a clear lysate it is possible to obtain plasmid DNA completely free of proteins, RNA, and chromosomal DNA. From partially purified plasmid the procedure allows the separation of the different forms. This technique was successfully applied to different plasmids ranging in size from 2.9 to 17.5 MDa. It is a preparative method yielding easily 500 micrograms of pBR322 from 1 liter of amplified culture. The plasmid is suitable for topoisomerase I, topoisomerase II, and EcoRI assays.