TY - JOUR
T1 - Pfg-nmr investigations of the binding of cationic neuropeptides to anionic and zwitterionic micelles
AU - Whitehead, Tracy L.
AU - Jones, Lucretia M.
AU - Hicks, Rickey P.
N1 - Funding Information:
This research was supported in part by funding from the National Science Foundation (NSF Grant CHE-92124521 [NMR Facilities, Mississippi Magnetic Resonance Facility], NSF Grant CHE-92055329 [MSU chemistry department computer facilities]), the National Institutes of Health (NIH Grant 1R15 NS 36389-01A1), the State of Mississippi, and Mississippi State University.
PY - 2004/2
Y1 - 2004/2
N2 - The mechanism by which peptides bind to micelles is believed to be a two-phase process, involving (i) initial electrostatic interactions between the peptide and micelle surface, followed by (ii) hydrophobic interactions between peptide side chains and the micelle core. To better characterize the electrostatic portion of this process, a series of pulse field gradient nuclear magnetic resonance (PFG-NMR) spectroscopic experiments were conducted on a group of neuropeptides with varying net cationic charges (+1 to +3) and charge location to determine both their diffusion coefficients and partition coefficients when in the presence of detergent micelles. Two types of micelles were chosen for the study, namely anionic sodium dodecylsulfate (SDS) and zwitterionic dodecylphosphocholine (DPC) micelles. Results obtained from this investigation indicate that in the case of the anionic SDS micelles, peptides with a larger net positive charge bind to a greater extent than those with a lesser net positive charge (bradykinin > substance P > neurokinin A > Met-enkephalin). In contrast, when in the presence of zwitterionic DPC micelles, the degree of mixed-charge nature of the peptide affects binding (neurokinin A > substance P > Met-enkephalin > bradykinin). Partition coefficients between the peptides and the micelles follow similar trends for both micelle types. Diffusion coefficients for the peptides in SDS micelles, when ranked from largest to smallest, follow a trend where increasing net positive charge results in the smallest diffusion coefficient: Met-enkephalin > neurokinin A > bradykinin > substance P. Diffusion coefficients when in the presence of DPC micelles, when ranked from largest to smallest, follow a trend where the presence of negatively-charged side chains results in the smallest diffusion coefficient: bradykinin > Met-enkephalin > substance P > neurokinin A.
AB - The mechanism by which peptides bind to micelles is believed to be a two-phase process, involving (i) initial electrostatic interactions between the peptide and micelle surface, followed by (ii) hydrophobic interactions between peptide side chains and the micelle core. To better characterize the electrostatic portion of this process, a series of pulse field gradient nuclear magnetic resonance (PFG-NMR) spectroscopic experiments were conducted on a group of neuropeptides with varying net cationic charges (+1 to +3) and charge location to determine both their diffusion coefficients and partition coefficients when in the presence of detergent micelles. Two types of micelles were chosen for the study, namely anionic sodium dodecylsulfate (SDS) and zwitterionic dodecylphosphocholine (DPC) micelles. Results obtained from this investigation indicate that in the case of the anionic SDS micelles, peptides with a larger net positive charge bind to a greater extent than those with a lesser net positive charge (bradykinin > substance P > neurokinin A > Met-enkephalin). In contrast, when in the presence of zwitterionic DPC micelles, the degree of mixed-charge nature of the peptide affects binding (neurokinin A > substance P > Met-enkephalin > bradykinin). Partition coefficients between the peptides and the micelles follow similar trends for both micelle types. Diffusion coefficients for the peptides in SDS micelles, when ranked from largest to smallest, follow a trend where increasing net positive charge results in the smallest diffusion coefficient: Met-enkephalin > neurokinin A > bradykinin > substance P. Diffusion coefficients when in the presence of DPC micelles, when ranked from largest to smallest, follow a trend where the presence of negatively-charged side chains results in the smallest diffusion coefficient: bradykinin > Met-enkephalin > substance P > neurokinin A.
KW - Dodecylphosphocholine (DPC)
KW - Micelles
KW - Neuropeptides
KW - Pulse Field Gradient Nuclear Magnetic Resonance (PFG-NMR) spectroscopy
KW - Sodium Dodecylsulfate (SDS)
KW - Substance P
KW - Tachykinins
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U2 - 10.1080/07391102.2004.10506949
DO - 10.1080/07391102.2004.10506949
M3 - Article
C2 - 14692800
AN - SCOPUS:1642433352
SN - 0739-1102
VL - 21
SP - 567
EP - 576
JO - Journal of Biomolecular Structure and Dynamics
JF - Journal of Biomolecular Structure and Dynamics
IS - 4
ER -