Action of Dinitrophenyl Amino Acids on Skeletal Muscle Proteins. I. Weak and Strong Absorption of Bis(Dinitrophenyl)Lysine and Bis(Dinitrophenyl)Ornithine by Myosin

Abstract

Below about 15°C in high ionic strength (0'5) phosphate buffer at neutral pH, the coloured compound bis(2,4.dinitrophenyl)-L-lysine (abbreviation bis-DNPlysine) was slowly but extensively absorbed from solution by rabbit skeletal muscle myosin. The absorption equations of Scatchard and of Klotz were not obeyed, thus suggesting that absorption did not involve independent sites. At higher temperatures, or if the myosin sulphydryl groups had been blocked with p-chloromercuribenzoate, absorption increased, often by as much as fivefold, and, moreover, a part of the absorbed bis-DNP-Iysine, probably corresponding to the "precipitation resistant" absorption reported previously, was strongly retained. Total absorption ofb~s-DNPlysine by myosin decreased slightly with increasing pH. At low temperatures bis-DNP-Iysine treatment induced the formation of small aggregates of myosin.