Spermidine inhibits degradation of yeast chromatin.

A procedure has been developed for the isolation of intact yeast chromatin from yeast nuclei. Autodigestion of chromatin observed during nuclear preparation was inhibited by the addition of 5 mM spermidine. The procedure is useful for the analysis of proteins associated with yeast chromatin.

An improved isolation procedure for yeast two-micrometer minichromosomes.

Two micrometer minichromosomes from Saccharomyces cerevisiae were isolated without detergent using metrizamide gradients. 2 µm minichromosomes showed a lower density in metrizamide gradients relative to genomic chromatin. Our results suggest a lower ratio of proteins to DNA in 2-µm minichromosomes as compared with genomic chromatin. The procedure described herein yields minichromosomes free of cellular chromatin and ribosomal protein contamination. This method may be useful for the isolation and characterization of other yeast minichromosomes.