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Surface-active properties of vasoactive intestinal peptide*
H Onyüksel1, B Bodalia, V Sethi
1Departments of Pharmaceutics and Pharmacodynamics, University of Illinois at Chicago, Chicago, IL, USA.
Peptides
|May 4, 2000
Summary
Human vasoactive intestinal peptide (VIP) aggregates in solution, forming micelles at 0.4 microM. This peptide also interacts with phospholipid monolayers, increasing surface pressure and suggesting a role in biological effects.
Area of Science:
- Biochemistry
- Biophysics
- Molecular Biology
Background:
- Vasoactive intestinal peptide (VIP) is a biologically active peptide.
- Understanding peptide aggregation and interaction with cell membranes is crucial for elucidating biological functions.
Purpose of the Study:
- To investigate the aggregation behavior of human vasoactive intestinal peptide (VIP) in aqueous solutions.
- To determine if VIP interacts with biomimetic phospholipid monolayers and affects surface pressure.
Main Methods:
- Utilized a custom Teflon trough and surface tensiometer to measure critical micellar concentration (CMC) and surface pressure.
- Assessed the interaction of VIP with dipalmitoylphosphatidylcholine (DPPC) phospholipid monolayers at physiological pH and temperature.
Main Results:
- The critical micellar concentration (CMC) of human VIP was determined to be 0.4 microM.
- VIP injection above CMC into the subphase of a DPPC monolayer caused a significant, concentration-dependent increase in surface pressure.
- This effect persisted for 120 minutes, indicating stable interaction and surface activity.
Conclusions:
- Human VIP exhibits aggregation in aqueous solution, forming micelles at micromolar concentrations.
- VIP demonstrates surface-active properties and interacts with phospholipid monolayers in a manner distinct from vasopressin.
- These aggregation and surface-active properties may contribute to VIP's biological functions in vivo.