Allen, Roger Laurance

2018-05-14T10:11:43Z

2018-05-14T10:11:43Z

1969

A major part of the work described in this thesis has been devoted to the problem of separating and rigorously purifying the two chicken hemoglobins. This problem has now been satisfactorily resolved and it is particularly hoped that the sort of criteria developed in this study for assessing protein purity will gain a wider application for the examination of other suitable proteins.

Because the assessment of protein purity has not always received critical attention, particularly in the field of hemoglobin biosynthesis in avian red cells, it may be necessar^ to revise some previously accepted ideas. Impurities in globin preparations may also prove to be responsible for many of the differences in results obtained by different groups of workers. A particular example of this, which has been examined during the present study, is the amino acid content of the cnicken globins. (Caha 1964; Van der Helm et al., 1953). Using the improved purification procedure described in section 1 of this thesis, it nas been possible to prepare highly pure globin preparations, which have been analysed for tueir amino acid content. It is confidently claimed that the analysis data presented in section 2 are the most reliable so far obtained for these two proteins.

The existence of highly purified samples of the chicken globins clearly opens the way to a more extensive study of the primary and secondary structures of these proteins, which however lies outside tne scope of the present work.

Tne sections of the thesis devoted to the purification procedure and amino acid analyses contain very important and necessary ground-work, without wnich no metabolic studies could be contemplated. In the final section, 3, a number of experiments are described which make use of the procedures and data previously presented

It has been shown tnat several methods of cell lysis result in tne formation of a pellet of debri3 which al.o contains hemoglobin. This hemoglobin has now been shown beyond doubt to have an important metabolic or physiological role in the cell. It has previously received little or no attention and this may go some way to explaining the manifest lack of agreement between groups of workers in the field.

Finally it has been shown that, when this bound fraction of hemoglobin is taken into account, the fractional rate of syntnesis of globin I is marginally, but reproducibly, higner than that of globin II, in the circulating blood cells. It has now been suggested that this finding may be a consequence of almost continually changing proportions of the two proteins as the red 144. calls nature. If this is so, it might "be predicted that in the most immature erythropoietic cells the rate of synthesis of glohin II might be higher than that of glohin I. In fact, Gaha et al. (I960) found that when chickens were injected with radioactive amino acids, the in vivo incorporation of these into globin II wa3 higher than into globin I. It would therefore clearly be desirable to investigate the biosynthesis of the two chicken hemoglobins in a population of cells from bone marrow. Juch a study might also give some insight into the systems of control which might be involved when very active cells synthesise two such proteins. Now that a really satisfactory method of purification and assessment of purity is available for these proteins, such a study might be attempted with some success

http://hdl.handle.net/1842/29682

The University of Edinburgh

Annexe Thesis Digitisation Project 2018 Block 18

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Studies on the biosynthesis of fowl hemoglobins

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PhD Doctor of Philosophy