periplasmisk

Periplasmisk is an adjective used in microbiology to describe components or processes pertaining to the periplasm—the space between the inner cytoplasmic membrane and the outer membrane in most Gram-negative bacteria. The periplasm is a gel-like compartment that contains the peptidoglycan layer, transport proteins, enzymes, and chaperones. It is physically bounded by the inner and outer membranes and is distinct from the cytoplasm and the external environment.

Functions carried out in the periplasm include protein translocation, folding, and maturation; nutrient acquisition and processing; and defense against environmental stresses. Proteins are routed across the inner membrane by secretion systems such as Sec and Tat; within the periplasm they encounter folding catalysts like SurA and Skp and disulfide-bond forming enzymes of the Dsb family. Periplasmic enzymes participate in nutrient hydrolysis, cell-wall remodeling, and detoxification, while periplasmic binding proteins facilitate transport and signaling.

Describing a protein or enzyme as periplasmisk denotes its localization to this compartment. The periplasm is an important interface for interactions with the outer membrane, including lipopolysaccharide assembly and outer-membrane protein quality control. In many Gram-positive bacteria, a classical periplasmic space is not present, though some species show analogous extracytoplasmic regions. The term periplasmisk therefore primarily describes the periplasmic localization in Gram-negative bacteria and related contexts.