Induction of Polymer Formation in Solutions of Bovine Pancreas Carboxypeptidase A by Aromatic Compounds^*

Protein-Carbohydrate interaction

“…Studies of the concentration dependence of sedimentation coefficient's led to the postulation of a rapid equilibrium involving the monomer and the dimer. In 2.5 M l;aCl, however, a bimodal pattern was obtained, and the concentration of the faster component increased with temperature (33). On the basis of this temperat'uredependence, t'he role of hydrophobic groups was indicated in the carboxypeptidase polymerization.…”

Heterogeneity of bovine carboxypeptidase A. I. Chromatographic purification of carboxypeptidase A (Anson)

“…formational changes in other regions of the molecule cannot be precluded by the static nature of such a model. Second, /3-phenylpropionate is known to bind at several loci in carboxypeptidase A including the active center (Bethune, 1965). If one or more of these loci in one of the variant enzymes are modified as a result of the amino acid replacement, the binding properties of the inhibitor will be different, thereby promoting separation in equilibrium chromatography.…”

The Polymerization of Carboxypeptidase A in Solutions Containing Sodium Chloride*

“…4 A further mode of polymerization of carboxypeptidase A, induced by the presence in the solvent of certain aromatic compounds, both involves these tyrosine residues at more than one site on the molecule and displays the same temperature dependence of polymer formation as does the polymerization occurring in 2.5 m NaCl (Bethune, 1965 In solutions containing (3-phenylpropionic acid, carboxypeptidase Ay and As form polymers stabilized by hydrophobic bonds. The extent of polymer formation varies directly with the temperature and the concentrations of protein, /3-phenylpropionic acid, and NaCl in the solvent.…”

“…The active center is one of the sites of polymerization, since removal of the zinc atom greatly depresses polymer formation. Acetylation with acetylimidazole also depresses formation; hence tyrosyl T A he physical chemistry of polymerization reactions of proteolytic enzymes and their potential pertinence to the chemical basis of catalytic specificity has been discussed recently (Bethune, 1965). Carboxypeptidase A, in particular, has been shown to undergo polymerization to either one of two products, depending upon the NaCl concentration in the solvent.…”