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SummaryNew methods of crosslinking enzyme molecules inside a matrix with or without Enzyme activity yields range bet,ween 30 and Even fragile enzyme systems, Inan inactive protein are described. 80% of the activity of the untreated preparations. for instance those using mobile cofactors, can be efficiently immobilized. creased resistance towards heat denaturation and proteolysis results.

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A RSTRACT: The artificial binding of enzymes into artificial membranes makes possible a study of the interaction between membrane structure and enzyme kinetics within a well-defined context. Artificial proteic membranes bearing immobilized enzymes are produced by using a co-cross-linking method. The influence of competitive and noncompetitive inhibitors on the kinetic behavior of enzymes in a membrane is described. The I n several systems (e.g., respiratory chain, fatty acid synthesis, etc.) the environment exerts a major influence on enzyme kinetics by new local conditions unpredictable from experiments performed in a homogeneous solution.Enzyme immobilization in an artificial membrane allows for the study of the influence of the structure on enzyme behavior in a well-defined context (Thomas and Caplan, 1974). In such studies, two factors play an important part in enzyme modulation: (a) the chemical composition and physical state of the carrier itself (hydrophobic or hydrophilic properties, nature and density of fixed charges); (b) the local concentration distribution of the reactants in the carrier. The last effect is the result of a balance between the flow of matter and enzyme reactions.The influence of the structure on enzyme behavior can be studied in any insoluble phase bearing immobilized enzymes. However the membrane is the easiest form from both experimental and theoretical point of view.In this way, Nims ( 1968), Pasynski et al.( 1 964), and Blumenthal et al. ( 1 967) have described associations between enzyme activities in solution and in an inert membrane, such as cellophane, to produce transport models, to study the interaction between diffusion and metabolism. Obviously, these models cannot show the resulting intramembrane phenomena.Goldman et al. (1965, 1968a,b, 1971) emphasized the limiting effect of substrate accessibility and of product elimination by using collodion-papain membranes. A pH-shift effect was shown in various conditions. Thomas et al. (1972a) gave an analysis of the effects of the diffusion constraints on glucose oxidase kinetics cross-linked in a proteic membrane. Mattiasson and Mosbach ( 1 97 1) have shown the interest of using an association of enzymes bound to particles as models of the effect of active-site vicinity on the behavior of sequential multienzyme systems. Several other papers dealt with the kinetic properties of the enzymes inside miscellaneous carriers (Kasche et al., I97 1 ;Sundaram and Laidler, 1972; Blaedel and Bogulaski, 1972;Kobayashi and Laidler, 1973). Among the above-mentioned models, those which give rise to a kinetic analysis were driven using the steady-state assumption, with irreversible monoenzyme systems in the absence of effectors. Ki-