Chymodiactin,Smith,US,1982
Chymopapain from papaya latex has been used in a study to assess the anthelmintic effect of natural plant cysteine proteinases against the gastrointestinal nematode, Heligmosomoides. Chymopapain from papaya latex has also been used in a study to investigate the preparation and identification of the rabbit′s antibody of chymopapain.
The undried latex of papaya is mixed with about three times its weight of
hundredth normal hydrochloric acid. To this mixture is then added dilute
hydrochloric acid (about normal) until a pH of substantially 2 has been
attained. The acidified latex is next allowed to stand over night or longer in a
cold place (0°C to 10°C). The material still in solution is then separated out,
by any convenient means, such as filtration through paper. From the soluble
portion, a small amount of inert protein is precipitated, by half saturation with
sodium chloride at about 10°C. The desired enzyme is next precipitated as a
nearly pure protein by raising the concentration of salt to full saturation, while
the pH is kept at a level of substantially 2, by the addition of normal alkali, if
necessary. The precipitate of protein is removed by any suitable means, and
may be kept as a thick paste out of contact with the air, and in the cold, The
keeping properties at higher temperatures are enhanced by addition of
enough alkali to the protein to bring its pH to 4.5-6.0.
This protein may be further purified, if desired, and eventually may be
crystallized, by redissolving the paste in saturated sodium chloride solution by
adjusting the pH to 4.5-6.0, and reprecipitating the enzyme protein by the
gradual addition of acid in the cold, until a pH of approximately 2.0 is
obtained; or, the purification may be accomplished by dissolving the protein in
acid at a pH of 2, and then precipitating the enzyme, by increasing the
concentration of salt.
When the activity and other properties of the several times recrystallized new
enzyme protein are compared with those of the uncrystallized precipitate
obtained in the first stages of the process, it is found that even in the first
stages, the enzyme is present in sufficiently pure form for most purposes
The enzyme cleaves amide linkages at the carboxyl side of arginine, leucine, glutamic acid, and alanine residues; as well as that of arginine esters. The optimum pH varies depending on the kind of substrate. For example, the pH optimum for casein digestion is 7.9, hemoglobin digestion is 4.0 and urea-denatured hemoglobin digestion is 7.0. Molecular mass of the enzyme is found to be 27 KDa.
