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Reaction characteristics and stability of a membrane‐bound enzyme reconstituted in bilayers of liposomes
Author(s) -
Kheirolomoom Azadeh,
Katoh Shigeo,
Sada Eizo,
Yoshida KenIchi
Publication year - 1991
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260370904
Subject(s) - liposome , membrane , chemistry , enzyme , biophysics , biochemistry , biology
The effects ensuing from the interaction between membrane‐bound sarcosine dehydrogenase and the surrounding lipids as well as the effects of membrane fluidity were described in this study. A 25‐fold activation was observed upon the reconstitution of the enzyme in bilayers of SUVs made of DMPC. The considerable decrease in K m and increase in V max suggest the induction of favorable conformational changes in both the substrate‐binding site and the catalytic site of the enzyme due to the lipid–protein interaction. In SUVs of negatively charged phospholipids, the enzyme retained its initial activity over 1 month. The break point in the Arrhenius plot of the activity of reconstituted enzyme was found at temperatures close to the gel–liquid crystalline transition point of the phospholipid showing that the activity is sensitive to the physical state of membrane phospholipids. Further, immobilization of the reconstituted enzyme by use of ENT prepolymer resulted in a high activity, whereas no remarkable activity was detected with the immobilized enzyme without reconstitution.