PERIPLASMIC ENZYMES IN GRAM-NEGATIVE BACTERIA

1. 1. In this article we have attempted to review the enzymatic component of the periplasmic space of gram-negative bacteria in terms of what constitutes a periplasmic enzyme, criteria for their localization, and their expression and functions in the intact cell. 2. 2. It is concluded that surface located enzymes are associated in a variety of ways with the inner and outer membranes, but that periplasmic enzymes are best denned operationally on the basis of their release during spheroplasting; this probably means they are not membrane associated. Some enzymes released by osmotic shock are not periplasmic. 3. 3. The expression of periplasmic enzymes in the intact cell depends on the presence of hydrophilic channels in the outer membrane. They may serve a variety of functions at the cell surface, the majority serving to degrade compounds in the medium to a utilizable form. © 1979.