Methods for the detection and determination of lipases (acylglycerol hydrolases) and preparation of assays are reviewed including substrates, conditions and screening. Some newer methods for the determination of lipase activity are discussed. Several of these are: (a) titrimetry, (b) colorimetry of Cu soaps of free fatty acids (FFA), (c) colorimetry of chromophores in the acyl chain of FFA or in glycerol, (d) radioassay, (e) gas liquid chromatography, (f) enzymatic treatment of FFA and measurement of the resulting products, and (g) direct immunological determination of the lipase. Examples and sensitivities are given and advantages and disadvantages are described.

Detection and determination of lipase (acylglycerol hydrolase) activity from various sources

The nucleophilic aromatic substitution for heteroatom through electrochemical oxidation of the intermediate σ-complexes (Meisenheimer complexes) in simple nitroaromatic compounds is reported for the first time (NASX process). The studies have been carried out with hydride, cyanide, fluoride, methoxy, and ethanethiolate anions and n-butylamine as a nucleophile, at the cyclic voltammetry (CV) and preparative electrolysis level. The cyclic voltammetry experiments allow for detection and characterization of the σ-complexes and they have led us to a proposal for the mechanism of the oxidation step. Furthermore, the power of the CV technique in the analysis of the reaction mixture throughout the whole chemical and electrochemical process is described.

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Nucleophilic aromatic substitution for heteroatoms: an oxidative electrochemical approach.

Focal phospholipases A2 group III injections induce cervical white matter injury and functional deficits with delayed recovery concomitant with Schwann cell remyelination.

This selective review covers the literature of thin-layer chromatography (TLC) and paper chromatography (PC) cited in Chemical Abstracts from December 5, 1983, through November 25, 1985, and Analytical Abstracts from November 1983 to November 1985. Also researched directly were the following important journals publishing papers on TLC and PC: the Journal of Chromatography (including its bibliography issues), Journal of High Resolution Chromatography and Chromatography Communications, Journal of Chromatographic Science, Chromatographia, Analytical Chemistry, JAOAC, and the special TLC issues of the Journal of Liquid Chromatography. Many of the inherent advantages of TLC that are obvious to workers familiar with high performance, quantitative theory and practice still are not appreciated adequately by the majority of people using chromatography. These include unrestricted access to the separation process; introducing magnetic, thermal, electrical, and other physical forces to improve resolution; high sample throughput; truly multidimensional separations; and the use of controlled multiple gradients. Many advantages of TLC relative to column chromatography were discussed in the Introductions to our 1982 and 1984 reviews of TLC in this Journal. No complete commercial robotics system specifically for TLC has been developed, but all necessary modules are available for such a system. The combination of robotics, with the continuedmore » development of theory, practice, and instrumentation will lead eventually to TLC systems that are unrivaled for speed, versatility, accuracy, precision, and sensitivity. 573 references.« less

Thin-layer and paper chromatography

Commercially available porcine pancreatic lipase was used to interesterify Canola oil and mixtures of Canola oil and lauric acid, Canola oil and trilaurin or Canola oil and fully hydrogenated high erucic acid rapeseed oil (HEAR stearin). The interesterification activity was evident only when the enzyme was adsorbed on diato-maceous earth and carefully dried under vacuum. Although the initial rate of reaction appeared to be fast, completion of the reaction required prolonged (up to 72 h) incubation period. The extent of interesterification appeared to be independent of the reaction temperature within the range of 20°C to 60°C. Positional analysis of fatty acids of interesterified oils showed that pancreatic lipase was specific for positions 1 and 3 of triacylglycerols. The physical properties of interesterified oils were markedly different from those of the starting mixtures. During interesterification, extensive rearrangement of fatty acids among triacylglycerols had taken place, resulting in new species of triacylglycerols.

Enzymatic Interesterification of Canola Oil

Enzymatic reactions on thin-layer chromatographic plates : I. Lipolysis of triglycerides and separation of products on a single plate

Enzymatic reactions on thin-layer chromatographic plates. II. Phospholipase A2 hydrolysis of phosphatidylcholine and separation of the products on a single plate.

Arun Kr. Das

Papers

Enzymatic reactions on thin-layer chromatographic plates : I. Lipolysis of triglycerides and separation of products on a single plate

Enzymatic reactions on thin-layer chromatographic plates. II. Phospholipase A2 hydrolysis of phosphatidylcholine and separation of the products on a single plate.

Enzymatic reactions on thin-layer chromatographic plates