In the present study, we have investigated the mechanism of affinity modulation of mll& by chymotrypsin. We first confirmed that mu-chymotrypsin could activate a143 (-7,000 molecules per platelet) without major intracellular signaling. However, we unexpectedly found that high concentrations of amiloride dose-dependently inhibited '%fibrinogen binding to the chymotrypsin-treated platelets, as we...

1. Acid-inactivated yeast invertase could not be regenerated in the presence of the proteolytic enzymes trypsin, pepsin, and chymotrypsin. 2. Certain foreign proteins of non-enzymatic nature partially inhibited the reactivation of acid-inactivated invertase. 3. Certain proteins as gelatin, lacto-globulin, and carbohydrate-free horse crystalbumin did not prevent the reactivation of invertase at ...

A convenient and rapid method for the photo-regulation of the proteolytic enzyme alpha-chymotrypsin is described. When alpha-chymotrypsin is coated with photolytic 1-(2-nitrophenyl)ethanol residues this not only markedly reduces the capability of the enzyme to digest both of the small substrates N-benzoyl-L-tyrosine ethyl ester and N-succinyl-L-phenylalanine p-nitroanilide, but also completely ...

"Aged" organophosphoryl conjugates of serine hydrolases differ from the corresponding "non-aged" conjugates in their striking resistance to nucleophilic reactivation. The refined X-ray structures of "aged" and "non-aged" organophosphoryl conjugates of gamma-chymotrypsin were compared in order to understand the molecular basis for this resistance of "aged" conjugates. "Aged" and "non-aged" cryst...

1. Acetylated chymotrypsinogen was prepared by the reaction of crystallized chymotrypsinogen with acetic anhydride at pH 6.7 and 4O, and purification of the product. End group analysis and Van Slyke amino nitrogen determination indicated that all the free Eand or-amino groups of the chymotrypsinogen molecule had been blocked by acetylation. 2. Activation of acetylated chymotrypsinogen by trypsi...

a-Chymotrypsin is a protein composed of three peptide chains linked by disulfide bridges, with amino-terminal half-cystine, isoleucine, and alanine residues.1 The latter two end groups appear upon the enzymic conversion of chymotrypsinogen A (which only contains the amino-terminal half-cystine residue) to a-chymotrypsin. The specificity of a-chymotrypsin as an enzyme (and of other chymotrypsins...