The peptic activation of acetyltrypsinogen

An Investigation of the Peptic Activation of Acetylated Trypsinogen*

“…However, two different sets of conditions were described. In one (Viswanatha et al, 1958), peptic digestion was carried out at 25°and pH 3.4, with a ratio of zymogen to pepsin of from 20:1 to 60:1. Presumably, the resulting product was the same regardless of the ratio used.…”

“…Preparation of the Active Derivative. Twice-acetylated trypsinogen (ATg) preparations were made using the method of Viswanatha et al (1958), except that inactivation of contaminant trypsin was performed with diphenylcarbamyl chloride (DPCC) or fluoride (DPCF) rather than diisopropylfluorophosphate (DFP), and the inactivation was performed after the acetylation of trypsinogen rather than before. (In an initial attempt to inactivate contaminant trypsin using TEPP before acetylation, it was found that the rate of autoactivation was faster than that of inactivation.…”

“…Peptic Activation. Activations with pepsin were carried out, as described by Viswanatha et al (1958) andViswanatha (1959), at initial pH values of 3.2 and 3.4 for from 48 to about 60 hr at 250 with pH controlled neither by buffer nor pH-Stat. Since the published procedures did not specify whether the pH was maintained constant at the initial value or not, activation was also carried out at pH 3.2, 3.4, and 3.8, kept constant by a Radiometer pH-Stat.…”

“…There have been a number of reports of the production of enzyme fragments possessing enzymic activity. Among the most interesting of these reports is that of Viswanatha and co-workers (Viswanatha et al, 1958; Liener and Viswanatha, 1959; Viswanatha and Liener, 1960) who reported an active fragment of trypsin that could be obtained from acetylated trypsinogen by the action of pepsin. This fragment was described as having a molecular weight of about 6000 (one-fourth that of trypsin), an N-terminal phenylalanine instead of the times that of trypsin (per active center).…”

Pepsinogen and Pepsin

“…Occasionally, the structure around the "active site" is not disrupted, though extensive cleavage of other parts of the molecule is observed (11). In the precursor, the active site may be protected, allowing other less essential components of the molecule to be removed (17). There is no predicting the course of such a study, but the variety of proteases and conditions that can be employed and the experience thus far, indicate its potential.…”