Current and voltage measurements were performed on Na,K-ATPase and sarcoplasmic reticulum (SR) Ca-ATPase. Measurements of current transients under short-circuit conditions and of voltage transients under open-circuit conditions were carried out by employing a solid supported membrane (SSM). Purified membrane fragments containing Na,K-ATPase or native SR vesicles were adsorbed on a SSM and were activated by performing substrate concentration jumps. Current and voltage transients were recorded in the external circuit, that are related to pump activity, and can be attributed to electrogenic events in the reaction cycles of the two enzymes. While current transients of very small amplitude are difficult to detect, the corresponding voltage transients can be measured with higher accuracy thanks to a much more favourable signal to noise ratio. Therefore, voltage measurements are preferable for the investigation of slow processes generating low current signals, e.g. for the analysis of low turnover transporters.
Electrogenic Ion Pumps Investigated on a Solid Supported Membrane: Comparison of Current and Voltage Measurements
RISPOLI, Giorgio;
2009
Abstract
Current and voltage measurements were performed on Na,K-ATPase and sarcoplasmic reticulum (SR) Ca-ATPase. Measurements of current transients under short-circuit conditions and of voltage transients under open-circuit conditions were carried out by employing a solid supported membrane (SSM). Purified membrane fragments containing Na,K-ATPase or native SR vesicles were adsorbed on a SSM and were activated by performing substrate concentration jumps. Current and voltage transients were recorded in the external circuit, that are related to pump activity, and can be attributed to electrogenic events in the reaction cycles of the two enzymes. While current transients of very small amplitude are difficult to detect, the corresponding voltage transients can be measured with higher accuracy thanks to a much more favourable signal to noise ratio. Therefore, voltage measurements are preferable for the investigation of slow processes generating low current signals, e.g. for the analysis of low turnover transporters.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
