PNNL

Abstract

A few years ago Milton, Milton and Kent1 described the total synthesis of the enzyme HIV-1 protease starting from D-amino acids. They found2 that the a-helices of the synthetic D-protease are left-handed, in contrast with the a-helices of the standard (L-amino acids) proteins, which are, of course, right-handed3. At present it is possible to study the stabilities of homochiral and mixed protein structures with the help of computer simulation techniques4,5. For example, using molecular mechanics calculations with the AMBER force field it was possible to show that DL-alanine in right-handed a-helices is 21.3 ± 3.4 kcal mol-1 less stable than right-handed a-helices made from L-alanine6. In the present paper we describe very accurate calculations which gives strong support to these findings.