 Short proteins can also be synthesized chemically by a family of methods known as peptide synthesis , which rely on organic synthesis techniques such as chemical ligation to produce peptides in high yield . Chemical synthesis allows for the introduction of non @-@ natural amino acids into polypeptide chains , such as attachment of fluorescent probes to amino acid side chains . These methods are useful in laboratory biochemistry and cell biology , though generally not for commercial applications . Chemical synthesis is inefficient for polypeptides longer than about 300 amino acids , and the synthesized proteins may not readily assume their native tertiary structure . Most chemical synthesis methods proceed from C @-@ terminus to N @-@ terminus , opposite the biological reaction . 
 Short proteins can also be synthesized chemically by a family of methods known as peptide synthesis , which rely on organic synthesis techniques such as chemical ligation to produce peptides in high yield . Chemical synthesis <a href='uninflect' title='1'><mark>allows</mark></a> for the introduction of non @-@ natural amino acids into polypeptide chains , such as attachment of fluorescent probes to amino acid side chains . These methods <a href='drop_aux' title='2'><mark>are</mark></a>useful in laboratory biochemistry and cell biology , though generally not for commercial applications . Chemical synthesis <a href='drop_aux' title='3'><mark>is</mark></a>inefficient for polypeptides longer than about 300 amino acids , and the synthesized proteins may not readily assume their native tertiary structure . Most chemical synthesis methods proceed from C @-@ terminus to N @-@ terminus , opposite the biological reaction . 
Short proteins can also be synthesized chemically by a family of methods known as peptide synthesis , which rely on organic synthesis techniques such as chemical ligation to produce peptides in high yield . Chemical synthesis allow for the introduction of non @-@ natural amino acids into polypeptide chains , such as attachment of fluorescent probes to amino acid side chains . These methods useful in laboratory biochemistry and cell biology , though generally not fir commercial applications . Chemical synthesis inefficient for polypeptides longer den about 300 amino acids , and the synthesized proteins may not readily assume their native tertiary structure . Most chemical synthesis methods proceed from C @-@ terminus to N @-@ terminus , opposite the biological reaction .