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

✍ Scribed by H. Joseph Goren; Ephraim Katchalski-Katzir; Mati Fridkin

Publisher
Wiley (John Wiley & Sons)
Year
1977
Tongue
English
Weight
743 KB
Volume
16
Category
Article
ISSN
0006-3525

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✦ Synopsis

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 blocked with either a dinitrophenyl or a t‐butyloxycarbonyl group. The γ‐carboxyl of glutamic acid was protected as the benzyl ester. Both the coupling reactions and the polymerization step were via the N‐hydroxysuccinimide active ester method. Thiolysis removed the dinitrophenyl group, while hydrogen bromide removed the t‐butyloxycarbonyl and the benzyl groups. The water‐soluble unblocked polymers obtained were fractionated on Sephadex G‐50 or Bio‐Gel P30. Fractions within a range of average molecular weights of 2,000 to 25,000 were isolated. Enzymatic oxidation of the acid hydrolyzate of the polymers revealed that no detectable racemization had occurred.

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Poly(L-histidyl-L-alanyl-α-L-glutamic ac
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## Abstract Studies have been made of the precipitation of poly‐L‐glutamic acid from dilute aqueous solutions, over the pH range where the α‐helical conformation is maintained. The major purpose is to establish the molecular conformation in the precipitate and to outline the mechanism of the precip