Fluorescence spectroscopy studies of the association of membrane and soluble forms of chromaffin granule dopamine-beta-monooxygenase to bipolar phospholipid liposomes and micelles.
The association of membrane and soluble forms of dopamine-beta-monooxygenase to liposomes and micelles made from phosphatidylcholine and lysophosphatidylcholine respectively has been studied using the fluorescence spectroscopy technique. As it was shown in our previous study these bipolar phospholipids activate the reaction catalyzed by the enzyme. Effects of pH and ionic strength on the association process were also studied, and efficiency of the association for apo- and holoenzyme was compared. The data obtained demonstrate that electrostatic attraction is involved in the association process. It was also shown that the membrane dopamine-beta-monooxygenase associated with phospholipid liposomes and micelles with higher efficiency than the soluble one did, which might be due to the involvement of the hydrophobic interactions in the association process. The results of the experiments also suggest that this process is specific and depends on the enzyme conformation, particularly on its quaternary structure. The participation of the hydrophobic peptide of the membrane dopamine-beta-monooxygenase in the formation and stabilization of the enzyme-phospholipid complex in vivo is proposed.
Pogosyan
A G
AG
Institute of Molecular Biology, National Academy of Sciences of Republic of Armenia, Yerevan. armine@mb.sci.am
Boyajian
A S
AS
Mailyan
K R
KR
Aivazyan
V A
VA
D000818:Animals; D002417:Cattle; D002837:Chromaffin Granules / Q000378:metabolism*; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D008244:Lysophosphatidylcholines / Q000378:metabolism*; D008823:Micelles; D010713:Phosphatidylcholines / Q000378:metabolism*; D012995:Solubility; D013050:Spectrometry, Fluorescence / Q000379:methods
D008081:Liposomes; D008244:Lysophosphatidylcholines; D008823:Micelles; D010713:Phosphatidylcholines; D004299:Dopamine beta-Hydroxylase