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Über die Kinetik der Amylolyse. Teil V. Untersuchung der SH‐Gruppen der Weizen‐beta‐Amylase und Nachweis der induzierten Anpassung
Author(s) -
László E.,
Holló J.,
Hoschke A.
Publication year - 1973
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19730251208
Subject(s) - chemistry , thiol , reagent , enzyme , substrate (aquarium) , stereochemistry , titration , amylase , medicinal chemistry , biochemistry , organic chemistry , oceanography , geology
In presence of substrate the inhibiting effect of thiol reagents is vastly decreasing. The enzyme molecule undergoes certain structural changes as a cause of „induced adaptation”, thus rendering the internal SH‐groups inaccessible. Those free SH‐groups on the surface play no significant role in the reaction catalyzed by the enzyme. On the Kinetics of Amylolysis. Part V. Examination of the SH‐Groups of Wheat‐β‐Amylase — Proof of Induced Adaptation. During titration of wheat‐β‐amylase with p‐chlorine mercury benzoate (pCMB) it was stated that the enzyme protein contains four sulfhydryl‐groups (SH‐groups) per molecule two of which are lying freely on the surface, whereas two are „hidden”. In absence of substrate thiol reagents instantly react with the SH‐groups. pCMB and N‐ethyl maleinimide cause an almost complete inhibition which is non‐competitive in the case of pCMB as was demonstrated in reaction kinetic tests.