Contents

05 June 1992
Vol 256, Issue 5062

About The Cover

A ``left-handed'' enzyme, HIV-1 protease (shown in front of the mirror as a dimer), that contains D-amino acids has been chemically synthesized. It preferentially cleaves peptide chains of D-amino acids (reaction shown below the molecule). The chemically synthesized ``right-handed'' form (the L-enantiomer, shown in the mirror) has reciprocal chiral specificity and preferentially cleaves commonly occurring L-amino acid peptides. See page 1445 and the Perspective on page 1403. [Computer graphics modeling and photography: Arthur Olsen, Yng Chen, and Garrett Morris. Additional illustration: Diana DeFrancesco]