The Phenomenon of the regulation of the catalytic activity of enzymes via changing their oligomeric composition in the system of reversed micelles of sodium bis(2‐ethylhexy)sulfosuccinate (AOT) in octane was studied using z‐chymotrypsin (CT) from bovine brain and alkaline phosphatase (AP) from calf intestinal mucosa. The dependences of the enzyme catalytic activity on the AOT hydration degree (W=[H2O][AOT]), the parameter determining the radius (r
4) of the inner cavity of micelles, usually represent the bell‐shaped curves. The maximal catalytic activity is observed at such Wo
when r
4 is equal to the size of the enzyme molecule. The position of this maximum strictly correlates with the enzyme oligomeric composition. Thus, in the case of CT this is observed at Wo
=12 when r
1 is equal to the radius (rp
) of the CT globule. In the case of artificially produced conjugate containing six cross‐linked CT molecules, this is observed at W
o=43 when r
4 is equal to the radius of the sphere surrounding the absolute octahedron composed of six CT globules. The dependence of the catalytic activity of AP on Wo represent a curve with two maxima that are observed when r
4 is equal to r
p of either AP monomer (W=17) or AP dimer (W
o=25), Ultracentrifugation experiments revealed that variation of W
o causes a change in the oligomeric composition of AP its transition from monomeric (W
o<20) to demeric form (W
o > 20). Hence, the observed maxima correspond to functioning of different oligomeric forms of AP.
R~¢ived 17 July 1,992Cell,free mmslation in reversed micclles (RM) of surf.'tctants in orllani¢ solvents is demonstrated usinl; as an oxamrA¢ the synthesis of human intcrlcukin,2 by the wheat germ translation system ~lubili~cd in Llrij 96 (olcyl-pol)'tl0]oxycthyle4~c ether) RM in ¢)'clohexan¢. The translation syst¢m components and the product were recovered from the RM system by a~tone pr~ipitation. The r~o~ry and translation reaction yields deixndcd on the delffee of suffactant hydration. The translation yields in Iirij 96 RM were clos~ to that observed in rel~ular aqueous tmiution, The ~ri.j 96 RM system is regarded as a promising media for ttm cell-free synthm~is of hydrophobia proteins. M~anwhil¢, no trandation r~ction was ob~rved in Aerosol OT (sodium bis(2-¢thylhexyl) sulfosu¢inata) RM in octane, which pr~umably is due to the ability of" Aero~ml OT to bind MI~:" ioa~ ncc~ey for the functionini~ of the translation apparatus.Call.fro, translation: lntcrlcukin: Micellar cnzymololw: Rcvcrz~ mS.lie
|, INTRODUCTIONThe phenomenon of enzyme catalysis in reversed micelles (RM), discovered in 1977 by Martinek et el, [1], is now under intensive study in dozens of laboratories (s¢¢ for r¢vicw [2][3][4][5][6]), The particular int,r¢st in this field is conditioned by the fact that RM systems provide unique possibiliti¢,~ for reconstructing the natural membrane microenvironm=nt of biopolymers and their supramol¢cular assemblies. They permit the deliberate variation ofa wid~ range of physico-chemical propcrtic, of this microcnvironment, e.g, surfactant hydration, type of packing etc. which is of great importance for studying the membrane regulation of biochemical proc-Although a lot of work on enzymes in RM systems has been done during the last decade, much less is known about the behavior of functional complexes of proteins and nucl¢ic acids in this microheterogen~ous Correslmmte.ce addrezx: S,N. Narnctkin.
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