Chiral discrimination of intermolecular interaction between a pair of alanine is studied using ab initio theory (HF/6-311++G**) with rigid geometry of molecules and also with relaxed geometry of the same using semi-empirical (PM3) level of theory. The energy optimizations of the homochiral pair (L-L) and heterochiral pair (D-L) of alanine molecules are carried out with variation in distance and orientation between the molecules. The study reveals interesting discrimination as a function of distance and orientation without any use of parameters for both rigid and relaxed optimization. The implication of the observed orientation dependence of the preferred homochirality in the process of peptide biosynthesis is discussed.