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Optical and other properties of a hydrocarbon‐soluble polypeptide, poly‐γ‐( n ‐dodecyl)‐ L ‐glutamate
Author(s) -
Smith Jerry C.,
Woody Robert W.
Publication year - 1973
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1973.360121203
Subject(s) - chemistry , helix (gastropod) , trifluoroacetic acid , solvent , dodecane , hydrocarbon , cyclohexane , dichloroacetic acid , hexane , circular dichroism , polyelectrolyte , chloroform , protein secondary structure , crystallography , organic chemistry , polymer , biochemistry , ecology , snail , biology
Abstract The polypeptide poly‐γ‐( n ‐dodecyl)‐ L ‐glutamate (PDLG) is soluble in hydrocarbon solvents such as hexane, cyclohexane, and dodecane. The CD spectra of PLDG in these solvents are reported here. These spectra are typical α‐helix spectra and show none of the wavelength shifts and magnitude changes displayed by partially helical proteins in membrane preparations. This observation rules out the possibility that the membrane protein CD spectra result from solvent effects. The PDLG helix is stable in dodecane up to at least 70 °C. However, it is easily disrupted by trifluoroacetic acid, with the helix–coil transition centered at 3% TFA in hexane. Viscosity measurements of PDLG in dry dichloroacetic acid exhibit polyelectrolyte effects which can be suppressed by addition of several percent water.