The activity of formate dehydrogenase from Candida boidinii (CbFDH) was stabilized at 60 degrees C through interaction with its cofactor (NAD(+) or NADH) in the liposomal aqueous phase. The activity of 8.0 mu M free CbFDH without liposomal encapsulation progressively decreased at 60 degrees C in Tris buffer of pH 8.5 following the first-order kinetics. Free CbFDH without cofactor showed the half-life of enzyme activity t(1/2) of 3.5 min, while t(1/2) increased to 22 and 236 min with 15 mM NAD(+) and 4.5 mM NADH, respectively. Turbidity measurements revealed that the free CbFDH and CbFDH/NAD(+) became their aggregate-prone states at 60 degrees C. For the liposomal CbFDH/cofactor systems, the cofactor-induced stabilization of CbFDH was also observed. Typically, the liposomal 6.0 mu M CbFDH/4.3 mM NAD(+) showed significantly large t(1/2) of 36 min compared to the corresponding free CbFDH/NAD(+) (t(1/2) = 8.9 min). Mixing of free CbFDH/NAD(+) with the enzyme-free liposomes resulted in the insufficient interaction between liposomes and CbFDH showing tip of 14 min. The results obtained demonstrate that the lipid membrane assists the formation of highly thermostable enzyme cofactor complex through stabilizing the structure of the liposome-encapsulated CbFDH. (C) 2010 Elsevier Inc. All rights reserved.