1. Circular dichroism studies on synthetic signal peptides
G L Reddy, R Nagaraj Biochim Biophys Acta. 1985 Oct 18;831(3):340-6. doi: 10.1016/0167-4838(85)90117-7.
Circular dichroism studies on synthetic peptides corresponding to the signal sequences of chicken lysozyme and Escherichia coli proteins, lambda-receptor and lipoprotein, have been carried out in trifluoroethanol. The peptides, (CH3)3-C-O-CO-Thr-Leu-Lys-Lys-Leu-Pro-Leu-Ala-Val-Ala-Val-Ala-Ala-Gly- Val-Met-Thr-Ala- Ala-Met-Ala-OCH3, (CH3)3-C-O-CO-Met-Lys-Ser-Leu-Leu-Ile-Leu-Val-Leu-Cys(benzyl)- Phe-Leu-Pro- Leu-Ala-Ala-Leu-Gly-OH and (CH3)3-C-O-CO-Leu-Val-Leu-Gly-Ala-Val-Ile-Leu-Gly- Thr-Thr-Leu-Leu- Ala-Gly-OCH3, corresponding to the signal sequences of lambda-receptor, lysozyme and the hydrophobic region of lipoprotein, respectively, show two negative bands at approx. 205 and 220 nm, characteristic of an alpha-helical conformation. Secondary structural features are discernible even in the shorter, 12-residue carboxy-terminal fragments of these signal peptides. A comparison of the conformation of the amino-terminal, central and carboxy-terminal fragments of lipoprotein signal sequence indicates that the central octapeptide fragment is more structurally ordered compared to the amino- and carboxy-terminal fragments.
2. Directed self-assembly of dipeptides to form ultrathin hydrogel membranes
Eleanor K Johnson, Dave J Adams, Petra J Cameron J Am Chem Soc. 2010 Apr 14;132(14):5130-6. doi: 10.1021/ja909579p.
The dipeptide amphiphile Fmoc-Leu-Gly-OH has been induced to self-assemble into thin surface-supported hydrogel gel films and gap-spanning hydrogel membranes. The thickness can be closely controlled, giving films/membranes from tens of nanometers to millimeters thick. SEM and TEM have confirmed that the dipeptides self-assemble to form fibers, with the membranes resembling a dense "mat" of entangled fibers. The films and membranes were stable once formed. The films could be reversibly dried and collapsed, then reswollen to regain the gel structure.
3. Energy-resolved mass spectrometry: a comparison of quadrupole cell and cone-voltage collision-induced dissociation
A G Harrison Rapid Commun Mass Spectrom. 1999;13(16):1663-70. doi: 10.1002/(SICI)1097-0231(19990830)13:163.0.CO;2-T.
Collision-induced dissociation (CID) can be effected in the interface region between atmospheric pressure ionization sources and single quadrupole mass analyzers. By varying the electric field in these cone-voltage CID experiments energy-resolved mass spectra can be obtained leading to breakdown graphs exploring the energy evolution of the fragmentation pathways. The breakdown graphs obtained from these cone-voltage CID studies are very comparable to those obtained by varying the collision energy in the quadrupole collision cell of a BEqQ mass spectrometer. The comparison has been made for the protonated peptides H-Leu-Gly-Gly-OH, H-Gly-Leu-Gly-OH, H-Gly-Gly-Leu-OH and Leu-enkephalin
