| Autor: |
G.V Schulz, M Marx-Figini |
| Rok vydání: |
1966 |
| Předmět: |
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| Zdroj: |
Biochimica et Biophysica Acta (BBA) - Biophysics including Photosynthesis. 112:81-101 |
| ISSN: |
0926-6585 |
| Popis: |
The quantity of cellulose synthesized on growing cotton bolls and the corresponding degree of polymerisation have been measured as a function of time. It was found that the biosynthesis proceeds in two distinct stages, beginning with a slow process yielding the “primary” cellulose with a non-uniform degree of polymerisation of about 2000–6000 followed by a more rapid process yielding a large amount of “secondary cellulose” with a high and uniform degree of polymerisation of about 14000 (mol. wt. 2.3·106). During the second stage the degree of polymerisation is independent of time. It is shown that the two kinds of cellulose correspond to the primary and secondary cell wall. In order to understand the formation of large uniform macromolecules of cellulose and their highly ordered arrangement in layers of equally constructed elementary fibrils, the following model for the biosynthesis of cellulose is proposed: A template with the lenght of a cellulose molecule (about 7 μ) is situated inside a protein or lipoprotein tubule, possibly in the fashion proposed by Ledbetter and Porter . The enzymic combination of activated glucose molecules with the cellulose chain along the template is associated with the folding of the chain. The synthesized and folded cellulose chain is bound at the growing end of the fibril by hydrogen bridges. The orientation of the microfibrils in particular directions may be regulated by the protoplasmic streaming. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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