 Protein engineering with homologous recombination develops chimeric proteins by swapping fragments between two parental proteins . These techniques exploit the fact that recombination can introduce a high degree of sequence diversity while preserving a protein 's ability to fold into its tertiary structure , or three @-@ dimensional shape . This stands in contrast to other protein engineering techniques , like random point mutagenesis , in which the probability of maintaining protein function declines exponentially with increasing amino acid substitutions . The chimeras produced by recombination techniques are able to maintain their ability to fold because their swapped parental fragments are structurally and evolutionarily conserved . These <unk> " building blocks " preserve structurally important interactions like points of physical contact between different amino acids in the protein 's structure . Computational methods like <unk> and statistical coupling analysis can be used to identify structural subunits suitable for recombination . 
