Liposomal Encapsulation of Yeast Alcohol Dehydrogenase with Cofactor for Stabilization of the Enzyme Structure and Activity
Yoshimoto, M; Sato, M; Yoshimoto, N; Nakao, K
| HERO ID | 4943190 |
|---|---|
| In Press | No |
| Year | 2008 |
| Title | Liposomal Encapsulation of Yeast Alcohol Dehydrogenase with Cofactor for Stabilization of the Enzyme Structure and Activity |
| Authors | Yoshimoto, M; Sato, M; Yoshimoto, N; Nakao, K |
| Journal | Biotechnology Progress |
| Volume | 24 |
| Issue | 3 (0 |
| Page Numbers | 576-582 |
| Abstract | Yeast alcohol dehydrogenase (YADH) with its cofactor nicotinamide adenine dinucleotide (NAD super(+)) could be stably encapsulated in liposomes composed of POPC (1-palmitoyl-2-oleoyl-sn-glycero-3- phosphocholine). The YADH- and NAD super(+)-containing liposomes (YADH-NADL) were 100 nm in mean diameter. The liposomal YADH and NAD super(+) concentrations were 2.3 mg/mL and 3.9 mM, respectively. A synergistic effect of the liposomal encapsulation and the presence of NAD super(+) was examined on the thermal stability of YADH at 45 and 50 degree C. The enzyme stability of the YADH-NADL was compared to the stabilities of the liposomal YADH (YADHL) containing 3.3 mg/mL YADH without NAD super(+) as well as the free YADH with and without NAD super(+). Free YADH was increasingly deactivated during its incubation at 45 degree C for 2 h with decrease of the enzyme concentration from 3.3 to 0.01 mg/mL because of the dissociation of tetrameric YADH into its subunits. At that temperature, the coexistence of free NAD super(+) at 3.9 mM improved the stability of free YADH at 2.3 mg/mL through forming their thermostable complex, although the stabilization effect of NAD super(+) was lowered at 50 degree C. The turbidity measurements for the above free YADH solution with and without NAD super(+) revealed that the change in the enzyme tertiary structure was much more pronounced at 50 degree C than at 45 degree C even in the presence of NAD super(+). This suggests that YADH was readily deactivated in free solution due to a decrease in the inherent affinity of YADH with NAD super(+). On the other hand, both liposomal enzyme systems, YADH- NADL and YADHL, showed stabilities at both 45 and 50 degree C much higher than those of the above free enzyme systems, YADH/NAD super(+) and YADH. These results imply that the liposome membranes stabilized the enzyme tertiary and thus quaternary structures. Furthermore, the enzyme activity of the YADH-NADL showed a stability higher than that of the YADHL with a more remarkable effect of NAD super(+) at 50 degree C than at 45 degree C. This was considered to be because even at 50 degree C the stabilization effect of lipid membranes on the tertiary and quaternary structures of the liposomal YADH allowed the enzyme to form its thermostable complex with NAD super(+) in liposomes. |
| Is Certified Translation | No |
| Dupe Override | No |
| Is Public | Yes |
| Keyword | Temperature effects; Alcohol dehydrogenase; Enzymes; Coexistence; Quaternary structure; Liposomes; Encapsulation; Protein structure; Cofactors; NAD; Lipid membranes; Thermal stability; Tertiary structure; phosphocholine; Turbidity; 2008) |