The free amino group of gramicidin S

Abstract

5-2,4-Dinitrophenyl-l-ornithine and a-2,4-dinitrophenyl-l-ornithine were prepd. by use of dinitro-fluorobenzene; m. p. 223[degree] (decomp.) and 227[degree] (decomp.), resp.; on a 66% methyl ethyl ketone-ether column, R = 0.12 and 0.07, resp. 2,4-Dinitrophenyl-gramicidin S was prepd. and hydrolyzed, and the free amino group was found to be 5-amino-ornithine. Gramicidin S is a cyclopeptide. Crystallographic study showed the needles or plates are elongated along [010], the former showing {001} and {101} while the latter show {100} and {001}. Orientation of the 3 refractive indices is [alpha]\\c, [beta]//b, [gamma]\\[alpha]. The unit cell dimensions are a = 10.08 A, b = 4.88 A, c = 32.9 A. Space grouping P 2, 2, 2. p calculated 1.4 for n = 4.