Siemion I Z, Siemion P J
Institute of Chemistry, Wroclaw University, Poland.
Biosystems. 1994;33(2):139-48. doi: 10.1016/0303-2647(94)90053-1.
It is shown that in the pairs of amino acids coded by the codons possesing identical bases in the first and second positions, the amino acids with R in the third position are of higher structural importance (which is reflected by higher values of (P alpha + P beta) sums of Chou-Fasman conformational parameters), and of stronger helix forming potentials (reflected by the differences (P alpha - P beta)), than the amino acids coded with Y. The same structural factors seem to be of importance for the codon choice in the case of amino acids coded by more than two codons. The amino acids which prefer alpha-helical over the beta-sheet conformation favour the codons with R in their third position, and those which favour the beta-sheet conformation favour the codons with Y in this position.
结果表明，在密码子的第一和第二位具有相同碱基的氨基酸对中，第三位为R的氨基酸具有更高的结构重要性（这通过Chou-Fasman构象参数的（Pα+Pβ）总和的较高值反映出来），并且比第三位为Y的氨基酸具有更强的形成螺旋的潜力（通过（Pα - Pβ）差异反映）。对于由两个以上密码子编码的氨基酸，相同的结构因素似乎对密码子选择也很重要。比起β-折叠构象，更倾向于α-螺旋构象的氨基酸更青睐第三位为R的密码子，而那些更倾向于β-折叠构象的氨基酸则更青睐此位置为Y的密码子。
