Demongeot Jacques, Glade Nicolas, Moreira Andrés
TIMC-IMAG, UMR CNRS 5525, Faculty of Medicine of Grenoble, University J. Fourier, 38 700 La Tronche, France.
Acta Biotheor. 2008 Jun;56(1-2):5-25. doi: 10.1007/s10441-008-9028-y. Epub 2008 Feb 14.
The genetic code has evolved from its initial non-degenerate wobble version until reaching its present state of degeneracy. By using the stereochemical hypothesis, we revisit the problem of codon assignations to the synonymy classes of amino-acids. We obtain these classes with a simple classifier based on physico-chemical properties of nucleic bases, like hydrophobicity and molecular weight. Then we propose simple RNA (or more generally XNA, with X for D, P or R) ring structures that present, overlap included, one and only one codon by synonymy class as solutions of a combinatory variational problem. We compare these solutions to sequences of present RNAs considered as relics, with a high interspecific invariance, like invariant parts of (t)RNAs and micro-RNAs. We conclude by emphasizing some optimal properties of the genetic code.
遗传密码已从其最初的非简并摆动版本进化而来，直至达到其目前的简并状态。通过运用立体化学假说，我们重新审视了密码子分配到氨基酸同义类别的问题。我们使用一个基于核酸碱基物理化学性质（如疏水性和分子量）的简单分类器来获得这些类别。然后，我们提出了简单的RNA（或更一般地说，XNA，其中X代表D、P或R）环结构，作为组合变分问题的解决方案，这些结构按同义类呈现且仅呈现一个密码子，包括重叠情况。我们将这些解决方案与被视为遗迹的现存RNA序列进行比较，这些RNA序列具有高度的种间不变性，如（t）RNA和微小RNA的不变部分。我们通过强调遗传密码的一些最优特性来得出结论。
