Publisher Summary This chapter presents a discussion of plasma cholinesterases. The whole field of cholinesterase polymorphism, and much of pharmacogenetics, is opened up by the clinical observation that in certain patients receiving succinylcholine, prolonged apnea developed. The best known clinical application of cholinesterase assay concerns the abnormally prolonged effect of the muscle relaxant succinylcholine that is found in a small proportion of patients. The cholinesterases are accepted as being synthesized in the liver and the assay of cholinesterase first became of interest to the clinician and to the clinical chemist as a test of liver function. Low serum cholinesterase activities are found in acute hepatitis, acute cirrhosis, and in liver metastases in those conditions where the hepatic synthesis of the protein is impaired. The synthesis of several other proteins is also reduced in such conditions, so that cholinesterase assay has been largely superseded as a test of liver function by measurements related to proteins such as albumin and prothrombin. Recommended procedures for collecting and storing plasma and serum specimens and laboratory procedures used for distinguishing the more common serum cholinesterase variants are also discussed in the chapter.

The plasma cholinesteerases: a new perspective.

Design of acetylcholinesterases for biosensor applications

The construction of electrodes, the behavior of which could be accurately analyzed and optimized is described. Two methods were used to construct such enzyme electrodes. A direct binding method, where a cation electrode was dipped into a solution of enzyme, albumin, and glutaraldehyde: a thin layer of cross-linked protein coated the electrode bulb. A two-step method, where an active membrane was first made by cross-linking these proteins by glutaraldehyde on a glass plate, then fitting with a silicone membrane onto a gas electrode (O2 or CO2). Both methods were used to construct glucose and urease electrodes measuring either NH4+ ions or CO2. Glucose oxidase and L-amino acid oxidase-pO2 electrodes were also developed. The theoretical and experimental behavior of these enzymatic membrane electrodes were compared using the analysis of product concentrations resulting from the association of diffusion with enzyme reaction in the active layer, and the optimum operating conditions were determined.

Construction and study of electrodes using crosslinked enzymes

CHAPTER 1 – Water-Insoluble Enzyme Derivatives and Artificial Enzyme Membranes

During the last three decades, numerous biological techniques have been developed as qualitative analytical methods to assess the effects of chemical pollutants on the environment, but only in the last 10 years have these methods been widely integrated into pollution-control programs. The increasing number of potentially harmful pollutants in the environment calls for fast, cost-effective analytical techniques to be used in extensive monitoring programs. As a result, the use of biological data to complement chemical analysis as well as the development of bio-detectors, such as immunoassays, biosensors and bioassays, has grown steadily in recent years. This overview article describes the principles, advantages and limitations of several biological methods for screening and diagnosis of organic compounds in environmental samples of water, sludge and sediments. It also describes the valuable and additional biological type of information that can be obtained through these determinations. This overview aims to describe the state of the art in Europe on sensors, biosensors, bioassays and immunochemical techniques for monitoring of water and soil pollution, with special attention to the screening methods developed under the European Commission’s 4th and 5th Framework Research Programs [1994–1998 (FP4) and 1998–2002 (FP5)].

J. Das

Papers

Immobilization of cholinesterase and urease.