Rate constants for actin polymerization in ATP determined using cross-linked actin trimers as nuclei.

Chemically cross-linked actin trimer, prepared from F-actin covalently cross-linked by N-W-p-phenylenebismaleimide, was used to nucleate the assembly of actin polymers under a variety of ionic conditions at 25 OC.Gel-filtered G-actin (5% labeled with N-pyrenyl iodoacetamide) was prepared in buffers containing 5 m M Tris.HCl, 0.2 r n ~