The localization of phosphatidylserine(PS) formed through the base-exchange reaction, and of serine base-exchange activity in rat brain microsomal membranes has been studied in this work. Trinitrobenzenesulfonic acid (TNBS) has been used to investigate the localization of PS, and proteolytic enzymes (trypsin, chymotrypsin and pronase) and mercury-dextran have been employed to study the localization of serine base-exchange activity. About one-half of the enzymic activity was resistant to the treatment with proteases and/or mercury dextran, indicating that at least a part of serine base-exchange is not accessibie to external surface reagents. The reaction of TNBS with membrane PS is slower and less complete than that with membrane phosphatidylethanolamine (PE). The reactivity of the PS newly-synthesized through the base-exchange pathway with TNBS is different from that of the bulk of membrane PS. Indeed, the former is able to react with 0.6 mM TNBS at 22°C, whereas the latter is not. This phenomenon could be due to a different localization and/or to a different binding to other membrane components of the newly-synthesized and of the bulk PS in brain microsomal membranes.
LOCALIZATION OF SERINE BASE-EXCHANGE REACTION IN RAT BRAINMICROSOMAL VESICLES
CORAZZI, Lanfranco;ROBERTI, Rita;BINAGLIA, Luciano;ARIENTI, Giuseppe
1987
Abstract
The localization of phosphatidylserine(PS) formed through the base-exchange reaction, and of serine base-exchange activity in rat brain microsomal membranes has been studied in this work. Trinitrobenzenesulfonic acid (TNBS) has been used to investigate the localization of PS, and proteolytic enzymes (trypsin, chymotrypsin and pronase) and mercury-dextran have been employed to study the localization of serine base-exchange activity. About one-half of the enzymic activity was resistant to the treatment with proteases and/or mercury dextran, indicating that at least a part of serine base-exchange is not accessibie to external surface reagents. The reaction of TNBS with membrane PS is slower and less complete than that with membrane phosphatidylethanolamine (PE). The reactivity of the PS newly-synthesized through the base-exchange pathway with TNBS is different from that of the bulk of membrane PS. Indeed, the former is able to react with 0.6 mM TNBS at 22°C, whereas the latter is not. This phenomenon could be due to a different localization and/or to a different binding to other membrane components of the newly-synthesized and of the bulk PS in brain microsomal membranes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.