Why there are only levo amino acids in the chemical composition of the living organisms.
In the structure of the DNA-histone system there are three kinds of elements which present spatial asymmetries: a) the D-deoxyribose molecules; b) the two strands of DNA which are wound counter-clockwise around the helical axis; c) the levo amino acids of the histones. This paper presents data and arguments which demonstrate that all these spatial asymmetries are interdependent and compose a unique system.
D000596:Amino Acids; D004247:DNA; D006657:Histones
D000596:Amino Acids; D006657:Histones; D004247:DNA