Lysine optical rotation

Conformations of the polymers were studied by CD and optical rotation measurements. Poly-L-lysine is known to exist in disordered, helical and -conformation, depending on the temperature, pH of the system and the solvent used. The side chain of the polymer has a significant effect on the backbone conformation. At neutral pH, poly-L-lysine exists in a random coil structure while at pH above 10, the e-amino group becomes a neutral form and the polymer undergoes transition to a helical structure. In order to elucidate the effect of base substituents on the conformation of poly-L-lysine, CD spectra of the copolymer were measured. 

The helix-coil transition in the copolymer clearly shows that the glutamic acid residues form the dominant helix (Table VII). There is no helix formation at alkaline pH owing to the lysine residues either by polarization of fluorescence or by optical rotation measurements in fact, both p and [ql]d decrease. The degree of polarization at pH 4 can be 85% reduced by 9M urea in both poly Glu97Lys3 and poly Glu63Lys37 (No. 3) this reflects destruction of the glutamic acid helix. 

The accumulation of -carboxy- -hydroxyadipic acid (homocitric acid) in the culture medium of the lysine-requiring yeast mutant, Ly4, grown on limiting amounts of lysine, has been demonstrated by Maragoudakis and Strassman (1966). Infrared spectra were used to affirm identification of the biologically formed acid, as were Ry s, optical rotations, and melting points. 

Abstract Aqueous biocompatible tribosystems are desirable for a variety of tissue-contacting medical devices. L-3,4-dihydroxyphenylalanine (DOPA) and lysine (K) peptide mimics of mussel adhesive proteins strongly interact with surfaces and may be useful for surface attachment of lubricating polymers in tribosystems. Here, we describe a significant improvement in lubrication properties of poly (dimethylsiloxane) (PDMS) surfaces when modified with PEG-DOPA-K. Surfaces were characterized by optical and atomic force microscopy, contact angle, PM-IRRAS, and X-ray photoelectron spectroscopy. Sudi surfaces, tested over the course of 200 rotations ( 8 m in length), maintained an extremely low friction coefficient (p) (0.03 0.00) compared to bare PDMS (0.98 0.02). These results indicate... 

---