Date of Award

Spring 1961

Document Type

Thesis

Degree Name

Master of Science

Department

Physics

Abstract

Within the last decade several important studies have been made on the large degradation of products of proteins. However, little work has been done on the intermediate degradation products. This study is concerned with the chromatographic separation of intermediate fragments from chrymotryptie hydrolysates of bovine plasma albumin and the determination of the molecular weights of the fragments. An automatic recording differential refractometer employing a differential cell of original design permitted the observation of chromatographic components as they were eluted f rom a column of Sephadex G-50. A fraction collector of original design collected 3 ml. fractions of the effluent. Three fractions were pooled together, successively, and the solvent eliminated by freeze-drying. Molecular weights of the peptide in each 9 ml. fraction were determined in the ultracentrifuge by using method II of Van Holde and Baldwin. Since the change in index of refraction is proportional to the concentration of solute, the area under the chromatographic curve is proportional to the amount of materiel eluted from the column. Hence, the ratio of the area under the curve corresponding to a particular fraction to the total area is equal to the amount of solute (q) in that fraction divided by the total amount (Q).

A molecular weight distribution was obtained by plotting the value of q/Q for each fraction against the molecular weight of that fraction.

Such a, distribution for the hydrolysis of bovine plasma albumin by chymotripsin was determined. The result s definitely indicate that the intermediate products are not composed of a continuum of molecular weights, but fall into several size groups.

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