{"name":"Kyte-Doolittle amino-acid hydropathy scale","publisher":"C Suite Biologics","canonical_page":"https://csuitebiologics.com/research-peptides/peptide-molecular-weight-calculator","date_modified":"2026-08-28","scope":"Hydropathy index values for the 20 standard amino acids used to calculate sequence GRAVY.","calculation":"GRAVY equals the sum of residue hydropathy values divided by sequence length.","source":"https://web.expasy.org/protscale/pscale/Hphob.Doolittle.html","publication":"https://pubmed.ncbi.nlm.nih.gov/7108955/","limitations":"GRAVY is a sequence-scale arithmetic mean and is not, by itself, a solubility, conformation, membrane association, or experimental measurement.","residue_count":20,"residues":[{"one_letter_code":"A","three_letter_code":"Ala","name":"Alanine","kyte_doolittle_hydropathy":1.8},{"one_letter_code":"C","three_letter_code":"Cys","name":"Cysteine","kyte_doolittle_hydropathy":2.5},{"one_letter_code":"D","three_letter_code":"Asp","name":"Aspartic acid","kyte_doolittle_hydropathy":-3.5},{"one_letter_code":"E","three_letter_code":"Glu","name":"Glutamic acid","kyte_doolittle_hydropathy":-3.5},{"one_letter_code":"F","three_letter_code":"Phe","name":"Phenylalanine","kyte_doolittle_hydropathy":2.8},{"one_letter_code":"G","three_letter_code":"Gly","name":"Glycine","kyte_doolittle_hydropathy":-0.4},{"one_letter_code":"H","three_letter_code":"His","name":"Histidine","kyte_doolittle_hydropathy":-3.2},{"one_letter_code":"I","three_letter_code":"Ile","name":"Isoleucine","kyte_doolittle_hydropathy":4.5},{"one_letter_code":"K","three_letter_code":"Lys","name":"Lysine","kyte_doolittle_hydropathy":-3.9},{"one_letter_code":"L","three_letter_code":"Leu","name":"Leucine","kyte_doolittle_hydropathy":3.8},{"one_letter_code":"M","three_letter_code":"Met","name":"Methionine","kyte_doolittle_hydropathy":1.9},{"one_letter_code":"N","three_letter_code":"Asn","name":"Asparagine","kyte_doolittle_hydropathy":-3.5},{"one_letter_code":"P","three_letter_code":"Pro","name":"Proline","kyte_doolittle_hydropathy":-1.6},{"one_letter_code":"Q","three_letter_code":"Gln","name":"Glutamine","kyte_doolittle_hydropathy":-3.5},{"one_letter_code":"R","three_letter_code":"Arg","name":"Arginine","kyte_doolittle_hydropathy":-4.5},{"one_letter_code":"S","three_letter_code":"Ser","name":"Serine","kyte_doolittle_hydropathy":-0.8},{"one_letter_code":"T","three_letter_code":"Thr","name":"Threonine","kyte_doolittle_hydropathy":-0.7},{"one_letter_code":"V","three_letter_code":"Val","name":"Valine","kyte_doolittle_hydropathy":4.2},{"one_letter_code":"W","three_letter_code":"Trp","name":"Tryptophan","kyte_doolittle_hydropathy":-0.9},{"one_letter_code":"Y","three_letter_code":"Tyr","name":"Tyrosine","kyte_doolittle_hydropathy":-1.3}]}