ANTIMUTAGENIC ACTIVITY OF CASEIN AGAINST MNNG IN THE ESCHERICHIA-COLIDNA-REPAIR HOST-MEDIATED ASSAY

The effect of caseinate and soy protein in the diet on the mutagenicit y induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was assessed in-vivo and ex-vivo in the DNA-repair host-mediated assay and liquid s uspension assay, respectively. Of the two proteins only casein showed a strong antimutagenic activity over the whole digestive tract, except in the stomach. It is suggested that the molecular structure of a pro tein determines its protective effect against mutagens: casein lacks s econdary and tertiary structure so that amino acids are more readily a vailable for interaction with the mutagen than with the amino acids in soy protein which is a globular protein. (C) 1997 Elsevier Science Ir eland Ltd.