We plan to continue along the five main chapters outlined in the progress report: 1/ The study on the energetic and structural coupling between tertiary and quaternary structures will be pursued in order to determine the eventual role of different phenomena on the refolding of the Tryptophanase after denaturation. The role of disulfide bonds during the folding of the reduced-denatured chymotrypsinogene will be further studied. 2/ Three allosteric enzymes are currently under study (glycogen phosphorylase b from rabbit skeletal muscle, pyruvate kinase and phosphofructokinase from E. coli). On the other hand, we begin to work on new protein factors which stimulate RNA transcription. 3/ The nature of the interactions between the two "globules" of the aspartokinase I-homoserine dehydrogenase I will be studied using chemical, genetic and immunological tools. 4/ a. The structure and function of the maltose permease-lambda receptor complex will be further investigated and a study of the mode of integration in the bacterial envelope will be initiated. b. The effect of cyclic AMP on the catabolite repression is studied with the help of natural and synthetic compounds acting as anatogonists of cyclic AMP. 5/ The main effort in this section will be the study of the physico-chemical properties of the cholinergic receptor proteins from Electrophorus electricus and Torpedo marmorata, in its purified and membrane bound forms.