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The interaction of phospholipase A2 with micellar interfaces. The role of the N-terminal region.
Metadata
Journalbiochemistry2.865Date
1975-Dec-16
Publication Type
Journal Article
Volume
1975-Dec-16 / 14 : 5387-94
Author
van Dam-Mieras MC , Slotboom AJ , Pieterson WA , de Haas GH
DoiPMIDMESH
Amines
Barium
Binding Sites
Calcium
Hydrogen-Ion Concentration
Kinetics
Lysophosphatidylcholines
Micelles
Pancreas
Phosphatidylcholines
Phospholipases
Protein Conformation
Trypsin
Abstract
The localization of the previously postulated interface recognition site (IRS) in porcine pancreatic phospholipase A2, required for a specific interaction between the enzyme and organized lipid-water interfaces, was investigated by ultraviolet difference spectroscopy, by measurements of the intrinsic fluorescence of the unique Trp residue, and by protection experiments against specific tryptic hydrolysis. Using the enzymically nondegradable substrate analogues: CnH(2n+1)(0-)OOCH2CH2N+(CH3)3-(H,OH), it is shown that the rather hydrophobic N-terminal sequence of the enzyme, viz., Ala-Leu-Trp-Gln-Phe-Arg, is directly involved in the interaction with the lipid-water interface. Besides hydrophobic probably also polar interactions contribute to the binding process. At neutral or acidic pH the presence of a salt bridge between the N-terminal alpha-NH3+ group and a negatively charged side chain stablizes the interface recognition site and allows the enzyme to penetrate micellar surfaces, even in the absence of metal ion. At alkaline pH, interaction of the enzyme with micellar interfaces requires the presence of Ca2+ (Ba2+) ions.
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2.9
Biochemistrybiochemistry
Metadata
LocationUnited States
FromAMER CHEMICAL SOC

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