Helix–coil transition in poly(γ‐benzyl‐L‐glutamate) and poly‐ε‐carbobenzoxy‐L‐lysine

Abstract

SynopsisIn this paper two points are considered: the methods of evaluating the helical content 8 and the calculation of the parameters of the transition from experimental data and its interpretation. The parameter AH obtained is in good agreement with the calorimetric one and v is found to be independent of temperature and solvent and in agreement with the ordinarily accepted value for poly(y-benzyl-L-glutamate). The different methods of estimating 8 are discussed for both polypeptides.

Conformation and Conformational Transitions of Poly-α-Amino Acids in Solution

“…Alternatively, the value of AH/tr~ can be obtained from the temperature dependence of 0 of a sample of very high degree of polymerization (theoretically infinite) around the midpoint of the transition (melting temperature Tin), using Equation 9, valid under these conditions Ra 112 9. (225,276,301,302,304,307,310,311). If AH is determined independently (by calorimetry) (123,301,302,305,313), one obtains ~ from Equation 9 and from the relationship AS = AH/T,~.…”

“…They are calculated from the temperature dependence of the degree of helicity (0) of number of samples with different chain length (304,308,309,312,314). The various procedures employed have been described in detail (123,226,(301)(302)(303)(304)(305)(306)(307)(308)(309)(310)(311)(312)(313)(314). Alternatively, the value of AH/tr~ can be obtained from the temperature dependence of 0 of a sample of very high degree of polymerization (theoretically infinite) around the midpoint of the transition (melting temperature Tin), using Equation 9, valid under these conditions Ra 112 9.…”

“…Large positive values for ~XH (>500 cal per mole residue) and AS (>2 were recorded for polyamino acids such as poly-~-carbobenzyloxy-~-ornithine (314), poly-e-carbobenzyloxy-L-lysine (123,307), and the methyl, ethyl, benzyl esters of poly-L-glutamic acid (123,281,(301)(302)(303)335), undergoing inverted transitions in organic solvents (e.g. ethylene dichloride or chloroform) the presence of strong acids (e.g.…”

Conformation Studies of Copolypeptides Composed of γ-Benzyl-L-Glutamate and γ-Methyl-L-Glutamate in Solution

“…4 -10 Such inverse transition has been found, for example, in the systems: PBLG in mixtures of DCA and 1,2-dichloroethane {DCE); 4 -6 • 8 in mixtures of DCA and 1,4-butylene dichloride; 9 in mixtures of DCA and octyl chloride, 9 and in mixtures of DCA and 1-dodecyl chloride; 9 PMLG in mixtures of DCA and DCE, 3 and poly(s-carbobenzoxy-L-lysine) (PCBL) in mixtures of DCA and chloroform, 9 and in mixtures of DCA and DCE. 11 PBLG, PMLG, and PCBL have some common characteristics due to their large side * Recently the family name was changed from Kanamori to Hayashi.…”