A spectrophotometric method for the detection of contaminant chymopapains in preparations of papain. Selective modification of one type of thiol group in the chymopapains by a two-protonic-state reagent

A simple spectrophotometric method for the detection of chymopapains A and B, contaminants in some preparations of papain (EC 3.422.2), was devised. If the amount of rapidly reacting thiol in the preparation, as determined by increase in A343 consequent on reaction with the two-protonic-state thiol titrant, 2,2′ -dipyridl disulphide, is greater at PH8-9 than at pH4, contamination by the chymopapains is in dicated.