Leucine aminopeptidase et naphtylamidases dans l’épiderme humain

Abstract

Résumé. L’action des naphtylamidases et de la leucine aminopeptidase de l’épiderme est étudiée sur 23 naphtylamides, la leucinamide et la leucyl-glycine au moyen de méthodes fluorométriques, isotopiques et spectrophotométriques. La comparaison avec d’autres tissus est discutée.

Acid hydrolases in blister fluid.

“…Good agreement with other investigators (Mier & van den Hurk, 1975;Hopsu-Havu & Jansen, 1969) was found for the enzyme characteristics of cathepsin Bi and cathepsin C. The Michaelis-Menten constants of arylamidase correspond well with the value (3-5Xio~*mol/l) found by de Bersaques (1968) for human epidermis, whereas Mier & van den Hurk (1975) reported lower values for guinea-pig epidermis. The results of thermal inactivation of cathepsin Bi are quite similar to those of Ali et al (1967), who found a loss of about 50% of its activity after heating at 52°C for 30 min.…”

Studies on the soluble and membrane-bound amino acid 2-naphthylamidases in pig and human epidermis

“…It is not yet clear whether or not the amino acid 2-naphthylamidases are peptidases, as the natural substrates are unknown, though it has been shown that their activities are distinct from those of the peptidases, cathepsins B, Bi, C and D (Barrett & Poole, 1969;McDonald et al, 1970). The fact that two types of amino acid 2-naphthylamidase exist in epidermis, together with the finding that the soluble enzymes, which account for the major portion of the amino acid 2-naphthylamidase activity in pig and human epidermis, do not exhibit Michaelis-Menten kinetics, must put in doubt the values of Michaelis constants previously reported for these enzymes in unfractionated homogenates of epidermis (De Bersaques, 1968;Mier & Van den Hurk, 1975).…”