ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Description / Table of Contents:
The so-called plastein consists of polypeptides formed via enzymatic synthesis from the enzymatic hydrolysate of proteins (in the studies chiefly zein was used as a protein and cryst. pepsin as an enzyme). By following step by step the course of the synthesis a rapid decrease of amino groups and a formation of low-molecular polypeptides can first be noted in the solution. Precipitation also begins rapidly but does not at first correspond to the decrease of amino nitrogen. After the decrease of amino nitrogen is no longer perceptible, the plastein precipitation is considerably increased. Thus the enzymatic synthesis of high-molecular polypeptides probably proceeds as follows:peptides in the hydrolysate (e.g. 4-6-peptides) → soluble intermediate peptides (e.g. 8-12-peptides) → insoluble polypeptides or plastein (36-100-peptides).If the protein is hydrolyzed to such an extent, that the average peptide size in the hydrolysate corresponds to 4-6-peptides, the above picture of the reactions is clear-cut. If the average peptide size in the hydrolysate corresponds e.g. to 10-peptides a slight decrease of amino nitrogen can be noted only in the beginning, later hydrolysis becomes dominant and plastein is precipitated, although amino nitrogen is liberally increased in the system. An X-ray diagram of plastein supports the above idea of the nature of plastein.
Notes:
Die Bildung von sog. Plastein in Zeinhydrolysaten durch krist. Pepsin wurde näher untersucht.Die erste Phase dieser enzymatischen Synthese ist durch eine rasche Verminderung der Aminogruppen und die Bildung niedermolekularer Peptide in der Lösung gekennzeichnet. Die ebenfalls rasch einsetzende Ausfällung entspricht zunächst nicht der Amino-gruppen-Abnahme und nimmt erst dann bedeutend zu, wenn diese nicht mehr nachweisbar ist.Die enzymatische Synthese der hochmolekularen Polypeptide verläuft demnach wahrscheinlich wie folgt:Peptide im Hydrolysat (z. B. 4-6-Peptide) → lösliche Zwischenpeptide (z. B. 8-12-Peptide) → unlösliche Polypeptide oder Plastein (36-100-Peptide).Ein Röntgendiagramm des Plasteins stützt die obenerwähnte Vorstellung über die Natur des Plasteins.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1951.020060110
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