> as lemmas

1953 M. Cohn et al. in Nature 12 Dec. 1096/2 Thus ‘constitutivity’ and ‘inducibility’ are properties of enzyme-forming systems, not of enzymes per se, and can be used as significant expressions only in a biological frame of reference, not in a chemical one. It should be stressed that the notions of constitutivity and inducibility are relative, not absolute; in any given biological system, a certain fraction of a particular enzyme-forming capacity may be constitutive, the remaining fraction inducible. For the sake of convenience, one may wish to refer to ‘an induced enzyme’ or to ‘a constitutive enzyme’; but it should always be kept in mind that these are shorthand expressions for ‘an enzyme the formation of which is largely or entirely inducible (or constitutive) in the particular organism concerned’.

1968 Biochimica et Biophysica Acta 166 589 (heading) Constitutivity of thymidine phosphorylase in deoxyriboaldolase negative strains: dependence on thymine requirement and concentration.

1975 Nature 6 Mar. 31/1 A mutation leading to strong constitutivity for a uric acid-xanthine permease in..Aspergillus nidulans has been found to be tightly linked to the putative structural gene whose expression it controls.

1978 Molecular & Gen. Genetics CLXVI. 256/2 The durO^h mutation causes high constitutivity of urea amidolyase synthesis.