✦ LIBER ✦

Poly(L-lysyl-L-alanyl-α-L-glutamic acid). II. Conformational studies

✍ Scribed by H. Joseph Goren; Carl R. McMillin; Alan G. Walton

Publisher: Wiley (John Wiley & Sons)
Year: 1977
Tongue: English
Weight: 685 KB
Volume: 16
Category: Article
ISSN: 0006-3525
DOI: 10.1002/bip.1977.360160712

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

The solution characterization of poly(Lys‐Ala‐Glu) is described. This polytripeptide is zwitterionic at neutral pH and is shown to take on a conformation which is dictated by the state of ionization, molecular weight, temperature, and solvent. The polypeptide is almost entirely α‐helical at low pH and temperature for polymers of greater than 25,000 molecular weight. Melting profiles for these conditions show t~m~ ∼ 20°C. Analysis of circular dichroism curves shows the α‐helical content to vary in a linear manner with molecular weight in the range 3000–30,000. At neutral pH the charged polypeptide is essentially random, but substantial α‐helix could be induced by addition of methanol or trifluoroethanol. At temperatures where the sequential polypeptide is a random coil, addition of trifluoroethanol produces a polymer which is mostly α‐helical but also contains an appreciable ammount of β‐structure. The infrared spectrum of a low‐molecular‐weight fraction assumed to be cyclo(Lys‐Ala‐Glu)~2~ was tentatively assigned a β‐pleated sheet structure.

A comparison of this polytripeptide in various ionization states with other polytripeptides containing L‐alanine and L‐glutamate or L‐lysine shows the α‐helix directing properties for the (uncharged) residues to lie in the order Ala > Glu > Lys.

📜 SIMILAR VOLUMES

Poly(L-lysyl-L-alanyl-α-L-glutamic acid)

✍ H. Joseph Goren; T. Fletcher; R. M. Epand 📂 Article 📅 1977 🏛 Wiley (John Wiley & Sons) 🌐 English ⚖ 651 KB

## Abstract Poly(Lys(Cbz)‐Ala‐Glu(OBzl)) was prepared by the self‐condensation of Lys(Cbz)‐Ala‐Glu(OBzl)‐ONSu in dimethylformamide. After deprotection of the side chains, the product was subjected to Sephadex G‐50 chromatography. The molecular weight of unfractionated and fractionated poly(Lys‐Ala‐

Viscosity and potentiometric measurement

Viscosity and potentiometric measurements of poly(L-histidyl-L-alanyl-α-L-glutamic acid) and poly(L-lysyl-L-alanyl-α-L-glutamic acid)

✍ H. Joseph Goren; Loretta Grandan; Alfred W. L. Jay; Noah Lotan 📂 Article 📅 1977 🏛 Wiley (John Wiley & Sons) 🌐 English ⚖ 629 KB

## Abstract Poly(His‐Ala‐Glu) and poly(Lys‐Ala‐Glu) were examined by viscosity and potentiometric titration. These measurements were interpreted in terms of the hydrodynamic size of the above sequential polypeptides. Effects of polymer, size and concentration, and solution‐salt concentration were d

Poly(L-histidyl-L-alanyl-α-L-glutamic ac

Poly(L-histidyl-L-alanyl-α-L-glutamic acid). I. Synthesis

✍ H. Joseph Goren; Ephraim Katchalski-Katzir; Mati Fridkin 📂 Article 📅 1977 🏛 Wiley (John Wiley & Sons) 🌐 English ⚖ 743 KB

## Abstract Poly(L‐histidyl‐L‐alanyl‐α‐L‐glutamic acid) has been prepared in order to test the acid–base catalytic ability of a carboxyl‐imidazole hydrogen‐bonded system. Two different blocked histidyl‐alanyl‐glutamic acid monomers were used in the polymerization step. The imidazole ring was blocke

Conformational changes of poly(L-histidy

Conformational changes of poly(L-histidyl-L-alanyl-α-L-glutamic acid) in solution. Transition pathways and conformational intermediates

✍ H. Joseph Goren; Mati Fridkin; Ephraim Katchalskikatzir; Noah Lotan 📂 Article 📅 1979 🏛 Wiley (John Wiley & Sons) 🌐 English ⚖ 597 KB

## Abstract The conformation and conformational transitions of poly(His‐Ala‐Glu) have been investigated by ir, nmr, and CD measurements. The results obtained—as well as the results of our previous investigations by potentiometric titration and hydrodynamic techniques [Goren et al., __Biopolymers__

Poly(L-histidyl-L-alanyl-α-L-glutamic ac

Poly(L-histidyl-L-alanyl-α-L-glutamic acid). II. Catalysis of p-nitrophenyl acetate hydrolysis

✍ H. Joseph Goren; Thea Fletcher; Mati Fridkin; Ephraim Katchalsi-Katzir 📂 Article 📅 1978 🏛 Wiley (John Wiley & Sons) 🌐 English ⚖ 643 KB

## Abstract The hydrolysis of __p__‐nitrophenyl acetate is catalyzed by imidazole, free in solution or as the side chain in poly(His‐Ala‐Glu). This is based on the observations that the reaction is first order in ester and first order in nonprotonated imidazole. Catalysis of __p__‐nitrophenyl aceta

Conformational study of poly(α-L-asparti

Conformational study of poly(α-L-aspartic acid)

✍ V. Saudek; Š. Štokrová; P. Schmidt 📂 Article 📅 1982 🏛 Wiley (John Wiley & Sons) 🌐 English ⚖ 538 KB

## Abstract The conformation of poly(α‐L‐aspartic acid) was investigated on a sample in which β‐bonds were not detected. CD and ir spectroscopy showed that poly(α‐L‐aspartic acid) passes through a conformational change induced by changes of the degree of ionization that is accompanied by precipitat