Microfibrils, relationship between

Figure 5.4 The relationship between change in microfibril width and degree of crystallinity following thermal treatment in wet and dry conditions, according to the data of Bhuiyan etal. (2000).

Hormone-treated pea seedlings generate two physically distinct cellulases (EC 3.2.1.4), with similar substrate specificities, Km values, and inhibitor sensitivities. They may be effectively separated by sequential extraction with buffer and salt and they appear to possess identical active sites but different apoprotein structures. The question arises of why this tissue should elaborate two hydrolases which catalyze the same reactions. The cellulase that forms first is synthesized by and accumulates in vesicles, where it would never encounter cellulose, while the other is concentrated on the inner wall microfibrils. It is suggested that only the latter cellulase functions to hydrolyze cellulose. A precursor/ product relationship between them could explain their distribution and developmental kinetics, but physical and chemical differences mitigate against this interpretation. 

Figure 3.25. Diagram illustrating the relationship between quarter-staggered collagen molecules in the microfibril (top) and the flexible and rigid regions of the amine acid sequence (bottom).The D period is one repeat containing 4 molecules (hole) followed by 5 molecules in cross-section (overlap). Mineral is deposited in the hole region in bone.

I. Tsekos, N. Orologas, and W. Herth, Cellulose microfibril assembly and orientation in some bangiophyte red algae Relationship between synthesizing terminal complexes and microfibril structure, shape, and dimensions, Phycologia, 38 (1999) 217-224. 

In order to examine the relationship between the microhardness of the MFC and those of its constituents (PET and PA6) including the moiphological entities, the two constituents of the MFC were subjected to the same thermal and mechanical treatments as the MFC and characterized after each step. Further, to evaluate the microhardness of the reinforcing microfibrils the additivity law was applied and the effect of crystal size on the structure formation was taken into account. 

Figure 4.6. Relationship between microfibril angle and longitudinal and tangential shrinkage in Pinus jeffreyi (Meylan, 1968).

Hirakawa Y and Fujisawa Y (1995) The relationships between microfibril angles in the S2 layer and latewood tracheid lengths in elite sugi trees (Cryptomeria japonica) clones. Mokuzai Gakkaishi, 41 2) 123-31... 

Fig. 15. The relationships between the unit cell of cellulose la and ip, and a schematic representation of the simultaneous occurrence of the two aUomorphs within the same microfibril. Such an event (boxed area) is Ukely to be the site of an amorphous moiety within the microfibril. (See Color Plate 8.)...

Haigler C.H. 1991. Relationship between polymerization and crystallization in microfibril biogenesis. In Haigler C.H. and Weimer RJ (eds.) Biosynthesis and Biodegradation of Cellulose. Marcel Dekker, New York, pp. 99-124. 

Giddings T.H. and Staehelin L.A. 1988. Spatial relationship between microtubules and plasma-membrane rosettes during the deposition of primary wall microfibrils in Closterium sp. Planta... 

Okuda K., Tsekos I., and Brown, Jr. R.M. 1994. Cellulose microfibril assembly in Erythrocladia subintegra Rosenv. an ideal system for understanding the relationship between synthesizing complexes (TCs) and microfibril crystallization. Protoplasma 180 49-58. 

The model extends the structural hierarchy proposed by Dobb, Johnson and Saville [374] for the aramids. Three distinct fibrillar elements have been noted microfibrils, on the order of 50 nm in size fibrils, on the order of 500 nm in size and macrofibrils, about 5 pm (5000 nm) across. The importance of this structural model is that it not only describes the structure of uniaxially oriented fibrous materials, but it also shows the fine structure of the thicker LCP forms of moldings and extrudates. In these thicker materials, process history and temperature affects macrostructures, such as skin-core, bands and layering (Fig. 5.85). The fiber structural model shows the arrangement of the fine structure within those macro units. This structural model improves the understanding of relationships between processes, structure and properties in LCPs. 

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