The reconstitution of a hybrid histone octamer containing avian ¹¹⁰Cys‐des‐thio‐histone H3 and sea‐urchin ⁷³Cys‐histone H4

A hybrid histone octamer was reconstituted from eythrocyte H2A and H2B, avian [110Cys‐des‐thio]histone H3 and the sea‐urchin sperm [73Cys]H4 variant. [110Cys‐Des‐thio]histone H3 was prepared by reaction of natural H3 with Raney nickel. The ability of the hybrid octamer to crystallise to the same form as the natural octamer demonstrated that the chemical modification of cysteine to alanine in H3 and the mutation from threonine to cysteine in sperm H4 do not alter histone‐histone interactions in the octamer. Since the sulfhydryl groups of both H4 molecules are fully accessible to 5,5′‐dithiobis(2‐nitrobenzoate) these residues provide suitable sites for the introduction of a single cysteine‐specific label per H4 molecule in the octamer. Copyright © 1988, Wiley Blackwell. All rights reserved