Enzymes in Analytical Chemistry Myer M. Fishman and Howard F. Schiff The City College. City University of New York, New York, N. Y . and Gilbert Associates, Inc.. Reading, Pa.
Enzymes continue to play an important role as one of the very significant tools for the analysis of a wide variety of materials which appear in foods, pharmaceuticals, clinical medicine, pesticides, etc. As such, and based on what is a high degree of specificity, they have been used to assay substrates (or products), coenzymes, and either activators or inhibitors of enzyme systems. They have been restricted only by the need for the careful control of pH, temperature, and frequently the kind of buffer employed. Many of the assay procedures have been well-standardized and have undergone little or no change with time. These are documented and can be found in several excellent references ( I , 2). In a review on the use of enzymes which appeared in this Journal ( 5 ) , an attempt was made to cover the period January 1970 through December 1971. This included papers which considered either changes in established procedure or provided new approaches to the same problem. Once again, this was done for the period January 1972 through December 1973. At the same time, there have been many interesting studies where either some special property of the substrate or the conditions of analysis were directed to establish an assay procedure for the enzyme itself. These have also been included. Some of the applications in the field of clinical chemistry have been considered and reviewed by Gochman and Young (6). Others have been studied and reported as a total picture involving the isolation, purification, and assay of an enzyme system. None of these have been included because they appear in standard references devoted to that purpose (3, 4 ) .
Myer M. Fishman has been Professor of Chemistry and Associate Dean of the College of Liberal Arts and Sciences at the City College of the City University of New York since 1969. He received his B.S. degree in chemistry from the City College and his M.S. and Ph.D. degrees in Biochemistry from the University of Minnesota. His research interests have included the use of dextran as a plasma expander, intravenous infusion of fat emulsions, carcinogensis of plastics, and interaction of macromoiecules with antibiotics and dyes. He is a member of the ACS, Sigma Xi, and the American Association for Cancer Research Howard F. Schiff received his B.S. degree in chemistry and M.A. degree in biochemistry from the City College of the City University of New York. He was a research assistant (analytical biochemist) in the Environmental Biology Division of the Boyce Thompson Institute for Plant Research, Yonkers, N.Y., and was a research assistant (biochemistry) in the Department of Medicine, Albert Einstein College of Medicine of Yeshiva University, Bronx, N Y. He is currently employed as ChemistiField Coordinator, Air Quality Control Department, Gilbert Associates Inc., in Reading, Pa. He is a member of the Division of Biochemistry and the Division of Air, Water, and Waste chemistry of the ACS; he is also a member of AAAS and ASTM
In the preparation of this review, it appeared to us, that, other than the usual changes in procedure which involve optical or radiochemical techniques, increased sensitivity a t lower concentrations, or the use of coupled enzyme systems, there were several areas for major change. These were the increasing use of automation, the increasing interest in electrochemical methods, and the use of water-insoluble enzymes. None of these are new, but they do warrant special consideration. The use of automated techniques has proceeded a t a very rapid pace. In clinical and hospital laboratories, where there is the continuing burden and sometimes the boredom of repetitive analyses, together with the increasing demand for much-needed assays, the use of semi-automated, automated, and computerized equipment has become almost routine. This has been accompanied by greater speeds of analysis. In addition, they are usually more accurate and reliable than the older manual assays. Another area of interest has been that involving the development of electrochemical methods, especially selective electrodes which are useful tools for biochemical and clinical analysis. Enzymes are either entrapped within a gel matrix around the electrode or are confined inside a cellophane membrane forming a liquid film around the electrode. This has made it possible to assay either the substrate or the product of such an enzyme-catalyzed reaction, without contamination or interference from the remainder of the solution. In the main, these electrodes have been either cation- or anion-sensitive, but there have been some interesting innovations with the aid of both PO2 and PCO2 electrodes. Finally, in the past few years, we have seen rapid and remarkable advances in the development of water-insoluble or immobilized enzymes. Enzymes have been covalently linked to water-insoluble polymers, or carriers, or retained in a solid matrix. These have lent themselves to the ease of removal of the enzyme from a system and its subsequent reuse. The activity of the enzyme has often been less than that of the free enzyme. However, in a field where much of the work has been restrained by the prohibitive cost of the enzyme, this promises to be a fruitful area for enhanced activity. The literature has become too voluminous to have been adequately covered in this paper; it is now being prepared for another review. In the meantime, the reader is referred to a paper by Silman and Katchalski ( 7 ) who reviewed the field in 1966. The format for this review, which follows, is similar to the one which was used in the previous article. The response from various readers suggested that this was not only acceptable, but desirable.
REFERENCES (1) Barman, T. E.. "Enzyme Handbook," Vol 1, 2, Springer-Verlag. New York. N.Y., 1960. (2) Bergmayer. H. U., Ed., "Methods of Enzymatic Analysis." Academic Press, New York, N.Y.. 1965. (3) Boyer, P. D.. Ed.. "The Enzymes." Academic Press, New York. N.Y.. 1971, 1972. (4) Colowick, S P.. Ed., "Methods of Enzymology,' Academic Press, New York. N.Y.. 1971. 1972. (5) Fishman, M. M.. Schiff, H . F.. Ana/. Chem.. 44, 543R (1972). (6) Gochman, N , Young, D. S., i b i d . . 45, 11R (1973). (7) Silman. I . H., Katchaiski, E., Ann Rev. Biochem.. 35, 873 (1966)
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