Liposome Aggregation: Promoted by Trypsin and Papain in the Absence of Cations

Abstract

Phospholipid vesicle aggregation is usually mediated by phospholipid-binding proteins such as the annexins in a Ca²⁺-dependent manner. Here, we describe aggregation of unilamellar liposomes by trypsin and papain in the absence of cations. Cations including Ca²⁺ inhibited the aggregation. While both trypsin and papain promoted aggregation of liposomes made of phosphatidylcholine and phosphatidylglycerol, only papain elicited aggregation of liposomes made of exclusively phosphatidylcholine. Incubation of trypsin for 30 min at 37°C destroyed its liposome aggregating activity, similar treatment had no effect on papain's. Chymotrypsin and pepsin had no liposome aggregating activity.