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Intracatenare Vernetzung von Gelatine mit Carbodiimid
Author(s) -
Gardi A.,
Nitschmann Hs.
Publication year - 1972
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19720550724
Subject(s) - chemistry , gelatin , reagent , covalent bond , melting point , molecule , polymer chemistry , chromatography , sepharose , peptide bond , amide , peptide , organic chemistry , biochemistry , enzyme
Under suitable conditions it is possible to introduce into dissolved denatured gelatin molecules intracatenar cross‐links. Working with 2% solutions of commercial gelatin (M n approximately 40000) at 40° and pH 5,75 and with water‐soluble carbodiimid as a condensing agent we succeeded in inserting 7–8 intracatenar amide bonds per molecule. The number of cross‐links introduced was determined by the decrease of free NH 2 and COOH groups. Using 4% solutions a gel melting point of the cross‐linked preparations below 0° was obtained as compared with the gel melting point of untreated gelatin at 28°. The low viscosity and the behaviour in gel chromatography on Sepharose 6B show that the cross‐linked peptide chains are fixed as rather dense coils. A small amount of the cross‐linking reagent remains covalently bound to the protein, as was shown with tritium labeled carbodiimid. The side reactions possibly responsible for this occurrence are discussed. The bonds between reagent and gelatin are fairly stable at acidic pH, but labile at alkaline pH. The results of optical measurements (UV. and CD.) on cross‐linked gelatin will be reported in another paper.