“…Therefore, it appears likely that endogenous proteins of Arthrobacter S, 55 were specifically protected in uiuo and in vitro against attack by intracellular proteases. This would correlate with the general observation that proteins with abnormal structures, including shortened chain length, are rapidly and specifically degraded in Arthrobacter S155 (Potier et al, 1985), and a wide range of exponentially growing cells (Carrier et af., 1984;Chaloupka & Strnadova, 1982;Goldberg & St John, 1976;Hipkiss et a f . , 1980;Kemshead & Hipkiss, 1974;Pine, 1972), while the bulk of endogenous proteins remain stable.…”