Inhibition of Chymotrypsin with Diisopropyl Phosphorofluoridate


IN a recent article Stein and Laidler1 described the inhibition of chymotrypsin by diisopropyl phosphorofluoridate (DFP). They found that even when the inhibitor-enzyme ratio was as high as 4 : 1 no complete inhibition was observed. This was contrary to the results of Jansen et al. 2, who found that when the molar ratio of DFP to enzyme was more than unity, there was practically 100 per cent inhibition.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Stein, B. R., and Laidler, K. J., Canad. J. Chem., 37, 1272 (1959).

  2. 2

    Jansen, E. F., Nutting, M. D. F., Jang, R., and Balls, A. K., J. Biol. Chem., 179, 189 (1949).

  3. 3

    Anson, M. L., J. Gen. Physiol., 22, 79 (1938).

  4. 4

    Schwert, G. W., Neurath, H., Kaufman, S., and Snoke, J. E., J. Biol. Chem., 172, 221 (1948).

  5. 5

    Hartley, B. S., and Kilby, B. A., Biochem. J., 50, 672 (1952).

  6. 6

    Jandorf, B. J., Michel, H. O., Schaffer, N. K., Egan, R., and Summerson, W. H., Disc. Farad. Soc., 20, 134 (1955).

  7. 7

    Kunitz, M., J. Gen. Physiol., 21, 601 (1938).

  8. 8

    Schwert, G. W., J. Biol. Chem., 190, 799 (1951).

  9. 9

    Hartley, B. S., and Kilby, B. A., Biochem. J., 56, 288 (1954).

  10. 10

    Ooms, A. J. J., thesis, Leyden (1960).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

OOMS, A. Inhibition of Chymotrypsin with Diisopropyl Phosphorofluoridate. Nature 190, 533–534 (1961).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.