S1 nuclease hydrolysis of single-stranded nucleic acids with partial double-stranded configuration.

The single-strand specific nuclease S1 from Aspergillus oryzae (EC 3.1.4.

Resolution of a spectrum of nucleoprotein species in sonicated chromatin.

Sonicated rabbit-liver chromatin is fractionated by ion-exchange chromatography on ECTHAM-cellulose, a weakly cationic adsorbent. The chromatographic procedure provides a series of fractions having a spectrum of thermal denaturation profiles. The earliest-eluting fractions melt cooperatively at a significantly higher temperature than bulk chromatin, and totally lack any of the components of chromatin that melt at low temperatures.

Immunochemical studies on the antigenic determinants required to elicit delayed and immediate hypersensitivity reactions.

Hartley and strain 2 guinea pigs were sensitized to chemically defined alpha-DNP(Lys)(n)-BuAm, alpha-DNP(Lys)(n)-, and (Lys)(n)-BuAm peptides and skin tested with individual members of these homologous series, related peptides and hapten-substituted proteins. The immediate skin response (Arthus) could be elicited with hapten-substituted tetra-, penta-, or hexamers, whereas both immediate and delayed skin responses could be provoked by the octamer or nonamer. The hapten is an integral part of the determinant for both immediate and delayed skin reactivity, since poly-L-lysine was unable to elicit either delayed or immediate reactions in sensitized animals.