| Autor: |
Masahiro Hori, Tomomasa Misato, Kazuo Kakiki |
| Rok vydání: |
1974 |
| Předmět: |
|
| Zdroj: |
Agricultural and Biological Chemistry. 38:699-705 |
| ISSN: |
0002-1369 |
| DOI: |
10.1080/00021369.1974.10861226 |
| Popis: |
Various derivatives of polyoxin C, other polyoxins and several uridine analogues have been known as competitive inhibitors of chitin-UDP acetylglucosaminyitransferase (EC 2.4.1.16, chitin synthetase). Their inhibitory activities were more or less dependent on pH. The variation of inhibitor constants Ki or Michaelis-Menten parameters Km and V with pH was investigated and the data obtained were plotted according to the method proposed by Dixon et al. From the results of the pKi-pH plots for the above competitive inhibitors, it was concluded that the ionized amino group at C−2″ position acted a very important role for the binding of polyoxins to chitin synthetase. The carbonyl oxygen atoms at C−1″ and of the carbamoyloxy group probably participated in the hydrogen bond formation with the enzyme. And pH scarcely influenced on the interaction between the carboxyl group at C−5″ and the enzyme. The results of the Dixon plots for variations of Km and V with pH suggested that an unionized imidazole group (pKa = 6.3) and an ionized amino group (pKa = 7.7) of chitin synthetase were concerned in the enzyme reaction. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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