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Investigations were conducted to determine the nature, type, functional properties and the amounts of different proteins found in bovine rumen tissue. Data concerning the effect of pH and salt concentration on the extractability of proteins from rumen tissue indicated that 92% of the proteins could be extracted in aqueous solutions at either pH 3.0 or 10.0. Rumen tissue proteins showed the least solubility in the pH range of 5 to 6. Two protein isolates having distinct compositional differences were obtained from the pH 10.0 aqueous extract by successively lowering the pH to 7.0 and 5.4. The supernatant remaining from the isoelectric precipitation at pH 5.4 contained one major sodium dodecyl sulfate (SDS) gel electrophoretic band corresponding to a subunit molecular weight of 67,000. However, bands corresponding to the four major contractile proteins were not detected. SDS-gel electrophoresis was used to identify the proteins in fresh rumen tissue, in the various extracts and in the protein isolates. The gels were subjected to densitometric analysis to obtain an estimate of the contractile proteins contained in the various samples. The protein isolate obtained at an isoelectric precipitation of pH 7.0 contained 28% myosin, 65% actin and 7% unidentified proteins but no troponin or tropomyosin. The isolate obtained at pH 5.4 contained 20% myosin, 40% actin, 19% troponin, 11% tropomyosin and 10% unidentified proteins. The protein extract at pH 10.0 contained 12% myosin, 35% actin, 9.5% troponin, 13% tropomyosin and 30.5% unidentified proteins. Based on 92% protein extractability at pH 10.0 and assuming only the stroma proteins to be insoluble at this pH, the protein composition of the fresh bovine rumen tissue was calculated to be 11% myosin, 32% actin, 9% troponin, 12% tropomyosin, 8% stroma, and 28% unidentified proteins. When the rumen tissue was homogenized in distilled water at neutral pH, 5% of the total soluble protein was myosin, 45% actin, 22% troponin and 20% tropomyosin. However, once the contractile proteins of the rumen tissue were purified, their solubility properties were similar to those of skeletal muscle contractile proteins. Contractile proteins purified from rumen and skeletal muscle yielded identical R [subscript m] values on SDS gel electrophoresis, and their estimated molecular weights were similar. Myosin from both rumen and skeletal muscle gave similar elution patterns on DEAE Sephadex A-50 columns. In each case, the major myosin peak emerged at a KC1 concentration of about 0.1 M. The ATPase activity of rumen myosin was lower at low ionic strengths but higher at high ionic strengths than that of skeletal myosin. The activity of both types of myosin was stimulated by Ca⁺⁺ and EDTA but inhibited by Mg⁺⁺. Amino acid analysis of rumen and skeletal myosins were similar, although rumen myosin had lower levels of lysine, aspartic acid, isoleucine, leucine and phenylalanine, and higher levels of glycine, valine, methionine and tyrosine, than skeletal myosin. Rumen and skeletal actin differed somewhat in amino acid composition. The most notable differences were the higher contents of glutamic acid and lysine in the rumen actin. The emulsifying capacity of the two rumen protein isolates were about 30% lower than that of the skeletal muscle proteins. However, the rumen protein isolates showed excellent stability and consistency which were judged to be comparable to those of skeletal muscle proteins. Rumen protein extracts and isolates showed excellent whippability and foam stability characteristics that were found to be equivalent to dried, reconstituted egg albumen. / Graduation date: 1977

Thesis (Ph. D.)--Oregon State University, 1972. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.Ag.Sc. 1972) from the Dept. of Agricultural Biochemistry and Soil Sciences, University of Adelaide.

No description available.

Thesis (Ph. D.)--University of Adelaide, Dept. of Animal Science, 1995? / Includes bibliographical references (leaves 122-138).

Thesis (M. Sc.(Agric.))( Animal science)-University of Pretoria, 2006. / Includes bibliographical references. Available on the Internet via the World Wide Web.

That certain bacteria in the rumen of sheep and cattle are attached to solid particles in the ruminal ingesta has been known for many years. In 1942 Baker published direct microscopical evidence that bacteria were attached to cellulose food particles and to starch granules in the rumen. The sites of attachment of these bacteria corresponded to sites of disintegration of the particles when viewed by polarised light. This indicated that at least bacteria attacking solid substrates such as cellulose and starch were attached to particles of ruminal ingesta. Van der Wath (1942) found rumen bacteria attached to particles of chemically pure cellulose and of crushed maize which he suspended in separate compartments of a pure silk bag inside the rumen of sheep. The bacteria associated with the particles of cellulose were mainly Gram negative rods , while clusters of iodophilic cocci were observed in most instances around the maize kernels . The latter organisms were isolated in pure culture and found to be heat-tolerant, short-chain, Gram positive cocci fermenting glucose, maltose, and other soluble sugars as well as starch. It was thus not surprising that many years later Schwartz et al (1964) obtained evidence which suggested that bacteria metabolising soluble substrates such as glucose also showed marked attachment to solid particles of ingesta.

No description available.

Thesis (M.Sc. (Agric.)(Animal and Wildlife Sciences)) -- University of Pretoria, 2007. / Includes bibliographical references. Available on the Internet via the World Wide Web.