Highest and lowest represented amino acids in the Cyanobacterial proteome Proteome-wide analysis of the cyanobacterial proteome revealed that Leu (11.104%) was the most abundant and Cys (1.014%) was the least abundant amino acid (Table 1). Other highly abundant amino acids included Ala (8.324%), Gly (6.837%), Ile (6.619), and Val (6.536%). Low abundant amino acids, in addition to the Cys, included Trp (1.436%), His (1.87%), Met (1.88%), and Tyr (2.983%) (Table 1, Fig 4).