Biomaterial Database

Sequential polypeptides. 2. Helix--coil transition in poly(gamma-benzyl epsilon-carbobenzoxy-L-lysyl-L-glutamate). 1977

S Itou, and D C Lee, and A Teramoto

Helix--coil transitions of an alternating copolypeptide poly(gamma-benzyl epsilon-carbobenzoxy-L-lysyl-L-glutamate) (poly[Lys(Z)-Glu(OBzl)]) in binary mixtures of dichloroacetic acid (DCA) and ethylene dichloride (EDC) were investigated by optical rotatory dispersion (ORD). The ORD data obtained were analyzed to evaluate the equilibrium constant s for helix formation and the cooperativity parameter sigma. The values of sigma1/2 are substantially independent of temperature and solvent composition, yielding 0.4 X 10(-2) on the average. The transition enthalpy deltaHc at the transition point decreases from 291 to 154 cal mol-1 as the DCA content is increased from 56 to 64 vol%. At about 20 degrees C and at 58 vol% DCA, poly[Lys(Z)-Glu(OBzl)] in binary mixtures of DCA and EDC undergoes a solvent-induced transition. This DCA content is intermediate between those for poly(gamma-benzyl L-glutamate) and poly(epsilon-carbobenzoxy-L-lysine) in the same binary solvent and close to that of an equimolar random copolymer of the two peptides. However, the s of poly[Lys(Z)-Glu(OBzl)] is not a geometrical mean of those of the parent homopolypeptides. This fact suggests that the helical conformation of the copolypeptide is stabilized by a conformational induction operative between adjacent residues.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008239	Lysine	An essential amino acid. It is often added to animal feed.	Enisyl,L-Lysine,Lysine Acetate,Lysine Hydrochloride,Acetate, Lysine,L Lysine
D010455	Peptides	Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS.	Peptide,Polypeptide,Polypeptides
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D005971	Glutamates	Derivatives of GLUTAMIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the 2-aminopentanedioic acid structure.	Glutamic Acid Derivatives,Glutamic Acids,Glutaminic Acids
D001593	Benzyl Compounds	Benzene derivatives that contain a benzyl group with the general formula Phenyl-CH2-R.	Compounds, Benzyl
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures