Comparison of the Protein Contents of Bovine Zymogen Granules and of Pancreatic Juice

<p>A zymogen granule fraction has been isolated from bovine pancreas by differential centrifugation under conditions designed to favor homogeneity at the expense of yield. The fraction has been examined in the electron microscope and found to contain a limited amount of contamination represented by clearly recognizable microsomes and mitochondria. These contaminants could account for a part of the 5% phospholipid and 1% nucleic acid found in the fraction by Schneider partition. The zymogen granule fraction was composed mainly of protein, about 95%. The protein content of the granules has been solubilized by exposure to pH 8, after which a membrane fraction could be isolated by centrifugation. This fraction is assumed to represent the smooth surfaced membranes which bound in situ the zymogen granules. The proteins present in the lysate of the granules and in the pancreatic juice have been fractionated by chromatography on DEAE cellulose and IRC-50 by the procedures employed by Keller, Cohen and Neurath. Trypsinogen, chymotrypsinogen A, ribonuclease, amylase, chymotrypsinogen B, procarboxypeptidase B, deoxyribonuclease and procarboxypeptidase A have been located in the chromatograms as 13 distinct peaks on the effluent curves. Complete recovery of the protein in pancreatic juice has been attained in this procedure; the recovery of the protein from the granule preparations was 10% less. Exact correspondence between the two chromatograms (juice and zymogen granule lysate) in terms of peak position, peak area, and enzyme specific activity has been observed. The chromatograms have revealed the presence of multiple forms of ribonuclease, in particular ribonuclease B; and have proved the existence of a new precursor of carboxypeptidase A, designated as procarboxypeptidase A', the molecular weight of which is approximately 25,000 less than procarboxypeptidase A. The quantitiative measurement of proteins of the juice and lysate provides a nearly complete and direct proof of the Heidenhain hypothesis; that the intracellular storage site of the protein of the pancreatic secretion is the zymogen granule.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Thesis

Year

1962

Author dc:creator

• Greene, Lewis Joel

Contributors dc:contributor

• Christophe Werner Hirs

• zymogen granules
• bovine pancreas
• protein fractionation
• pancreatic enzymes
• DEAE cellulose chromatography
• Heidenhain hypothesis
• Life Sciences

Repository record dc:identifier

https://digitalcommons.rockefeller.edu/student_theses_and_dissertations/577

OAI identifier oai:identifier

oai:digitalcommons.rockefeller.edu:student_theses_and_dissertations-1582