1.2 GRAVY Calculations

The GRAVY (Grand Average of Hydropathy) value for a peptide or a protein is calculated as the sum of hydropathy values10 of all the amino acids, divided by the number of residues in the sequence. The GRAVY index can be used to measure the hydrophobicity of a specific peptide/protein in the sample. The values used for the different amino acids are the following ones:

• Ala: 1.800
• Arg: -4.500
• Asn: -3.500
• Asp: -3.500
• Cys: 2.500
• Gln: -3.500
• Glu: -3.500
• Gly: -0.400
• His: -3.200
• Ile: 4.500
• Leu: 3.800
• Lys: -3.900
• Met: 1.900
• Phe: 2.800
• Pro: -1.600
• Ser: -0.800
• Thr: -0.700
• Trp: -0.900
• Tyr: -1.300
• Val: 4.200