Open AccessA New Principle of Regulation of Enzymic Activity
Author(s) -
TSCHESCHE Harald,
MACARTNEY Henry W.
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb05687.x
Subject(s) - biochemistry , chemistry , peroxidase , glutathione reductase , glucose oxidase , glutathione , hydrogen peroxide , glutathione peroxidase , gpx3 , pentose phosphate pathway , gpx1 , catalase , lactoperoxidase , enzyme , glycolysis
Latent collagenase form human polymorphonuclear leukocytes was isolated and shown to be activatable by disulfides, e.g. cystine, oxidized glutathione and insulin. Activation proceeds via a disulfide‐thiol exchange mechanisms by which the active proteinase ( M r 65500–67000) is released from the inactive latent enzyme ( M r 91000–94000) which is a mixed disulfide of an inhibitor ( M r 20000–25000) and the collagenase [Macartney and Tschesche (1980) FEBS Lett. 119 , 327‐332]. In a system in vitro the activation can be coupled to the glutathione cycle. Reduced glutathione and hydrogen peroxide in the presence of any of the enxymes glutathione peroxidase, NADH peroxidase, lactoperoxidase, horse radish peroxidase or human leukocyte myeloperoxidase activate the latent collagenase. Pre‐incubation of the peroxidase with the inhibitor sodium azide prevents the activation of the latent enzyme via hydrogen peroxide and reduced flutathione. The oxidizing equivalents can also be generated by employing the hydrogen‐peroxide‐generating system of glucose and glucose oxidase. The peroxidase‐catalysed activation by the glucose/glucose oxidase system can be inhibited by including either catalase or glutathione reductase in the activating system. NADH also inhibits the glucose‐coupled activation system, but this effect can be counteracted by including NADH peroxidase. The result indicate that the activation of the latent collagenase can be regulated by the glutathione cycle. The activation could be coupled in vitro to the glucose metabolism via the system glucose/glucose oxidase. Regulation in vitro might perhaps be coupled to the phagocytosis‐associated respiratory burst known to be linked to the hexose monophosphate shunt activity of the cell. In an experiment in vitro , with the concentrations of reduced and oxidized glutathione normally found in vivo , the glutathione cycle could be used either to activate or to inactivate the latent collagenase, depending on the addition of either hydrogen peroxide as oxidizing equivalents or NADPH or NADH as reducing equivalents. This provides the first example in which regulation of proteolyticactivity activity could be linked to the glutathione redox potential of the cell.