sedimentation constant

n.

A unit of time, usually between 1X10-13 and 200X10-13 per second, used in calculating the molecular weight of proteins as a function of their rate of movement during centrifugation.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.