You are not currently logged in.
Access JSTOR through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Substrate Activation of β-(1 → 3) Glucan Synthetase and Its Effect on the Structure of β-Glucan Obtained from UDP-D-Glucose and Particulate Enzyme of Oat Coleoptiles
C. M. Tsai and W. Z. Hassid
Vol. 51, No. 6 (Jun., 1973), pp. 998-1001
Published by: American Society of Plant Biologists (ASPB)
Stable URL: http://www.jstor.org/stable/4263259
Page Count: 4
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
UDP-D-glucose, at a micromolar level in the presence of MgCl2 and oat (Avena sativa) coleoptile particulate enzyme which contains both β-(1 → 3) and β-(1 → 4) glucan synthetases, produces glucan with mainly β-(1 → 4) glucosyl linkages. An activation of β-(1 → 3) glucan synthetase by UDP-D-glucose and a decrease in the formation of β-(1 → 3) glucan in the presence of MgCl2 have been observed. However, at high substrate concentration (≥ 10-4 M), the activation of β-(1 → 3) glucan synthetase is so pronounced that the formation of β-(1 → 3) glucosyl linkage predominates in synthesized glucan regardless of the presence of MgCl2. These observations may explain the striking shift in the composition of glucan of particulate enzyme from a β-(1 → 4) to β-(1 → 3) glucosyl linkage when UDP-D-glucose concentration is raised from a low concentration (≤ 10-5 M) to a higher concentration (≥ 10-4 M). Besides UDP-D-glucose, CDP-D-glucose can also serve as substrate for the formation of β-(1 → 3) glucan in the presence of β-(1 → 3) synthetase.
Plant Physiology © 1973 American Society of Plant Biologists (ASPB)