抄録
αs1-Casein can be made either soluble or insoluble by adjusting the concentration of coexisting calcium ions. In this study, we tried to make a soluble-insoluble interconvertible enzyme through the formation of a conjugate of an enzyme and αs1-casein using a heterobifunctional crosslinking reagent, N-succinimidyl 3-(2-pyridyldithio)propionate. The conjugate of phosphoglyceromutase and native αs1-casein did not exhibit sufficient calcium-dependent precipitation. However, conjugates of enzymes (phosphoglyceromutase, enolase or peroxidase) and αs1-casein polymerized by transglutaminase precipitated almost completely in the presence of more than 50mM CaCl2. Most of the enzyme conjugates precipitated as calcium casemates could be solubilized reversibly with EDTA, without a significant loss of activity. A mixture of the enzymea-polymerized αs1-casein conjugates prepared with phosphoglyceromutase, enolase and pyruvate kinase could catalyze sequential reactions which convert D-3-phosphoglycerate into pyruvate with the same efficiency as a mixture of free enzymes. These results indicate that conjugates of enzymes and polymerized αs1-casein can be useful as soluble-insoluble interconvertible enzymes.
