title: A plea for a comparative approach to evaluation of the physiological significance of regulatory mechanism observed in in vitro studies.
abstract: Regulatory mechanisms proposed on the vasis of in vitro studies using purified enzymes should be evaluated for their physiological significance in different species and under various conditions. The procedures presently employed for such evaluation are examined, and it is suggested that difficulties of application or interpretation arise, especially in studies on highly differentiated organisms. The use of comparative enzymology as an alternative approach to this problem is proposed, using in the main data obtained in studies on pyruvate carboxylase to illustrate the potential of this method. Some problems which arise in the use of comparative studies in this context are considered.
mesh_terms: D000818:Animals; D002384:Catalysis; D004798:Enzymes / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D010828:Physiology, Comparative; D011766:Pyruvate Carboxylase / Q000378:metabolism; D012107:Research Design
chemical_list: D004798:Enzymes; D011766:Pyruvate Carboxylase