50 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classification

BACKGROUND: Physicochemical properties are frequently analyzed to characterize protein-sequences of known and unknown function. Especially the hydrophobicity of amino acids is often used for structural prediction or for the detection of membrane associated or embedded β-sheets and &#945...

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Autores principales: Simm,Stefan, Einloft,Jens, Mirus,Oliver, Schleiff,Enrico
Lenguaje:English
Publicado: Sociedad de Biología de Chile 2016
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Acceso en línea:http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602016000100031
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spelling oai:scielo:S0716-976020160001000312016-12-0150 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classificationSimm,StefanEinloft,JensMirus,OliverSchleiff,Enrico Hydrophobicity scale Transmembrane sheets Transmembrane helix Beta-sheet Amino acid pattern Alternate hydrophobicity BACKGROUND: Physicochemical properties are frequently analyzed to characterize protein-sequences of known and unknown function. Especially the hydrophobicity of amino acids is often used for structural prediction or for the detection of membrane associated or embedded β-sheets and α-helices. For this purpose many scales classifying amino acids according to their physicochemical properties have been defined over the past decades. In parallel, several hydrophobicity parameters have been defined for calculation of peptide properties. We analyzed the performance of separating sequence pools using 98 hydrophobicity scales and five different hydrophobicity parameters, namely the overall hydrophobicity, the hydrophobic moment for detection of the α-helical and β-sheet membrane segments, the alternating hydrophobicity and the exact β-strand score. RESULTS: Most of the scales are capable of discriminating between transmembrane α-helices and transmembrane β-sheets, but assignment of peptides to pools of soluble peptides of different secondary structures is not achieved at the same quality. The separation capacity as measure of the discrimination between different structural elements is best by using the five different hydrophobicity parameters, but addition of the alternating hydrophobicity does not provide a large benefit. An in silico evolutionary approach shows that scales have limitation in separation capacity with a maximal threshold of 0.6 in general. We observed that scales derived from the evolutionary approach performed best in separating the different peptide pools when values for arginine and tyrosine were largely distinct from the value of glutamate. Finally, the separation of secondary structure pools via hydrophobicity can be supported by specific detectable patterns of four amino acids. CONCLUSION: It could be assumed that the quality of separation capacity of a certain scale depends on the spacing of the hydrophobicity value of certain amino acids. Irrespective of the wealth of hydrophobicity scales a scale separating all different kinds of secondary structures or between soluble and transmembrane peptides does not exist reflecting that properties other than hydrophobicity affect secondary structure formation as well. Nevertheless, application of hydrophobicity scales allows distinguishing between peptides with transmembrane α-helices and β-sheets. Furthermore, the overall separation capacity score of 0.6 using different hydrophobicity parameters could be assisted by pattern search on the protein sequence level for specific peptides with a length of four amino acids.info:eu-repo/semantics/openAccessSociedad de Biología de ChileBiological Research v.49 20162016-01-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602016000100031en10.1186/s40659-016-0092-5
institution Scielo Chile
collection Scielo Chile
language English
topic Hydrophobicity scale
Transmembrane sheets
Transmembrane helix
Beta-sheet
Amino acid pattern
Alternate hydrophobicity
spellingShingle Hydrophobicity scale
Transmembrane sheets
Transmembrane helix
Beta-sheet
Amino acid pattern
Alternate hydrophobicity
Simm,Stefan
Einloft,Jens
Mirus,Oliver
Schleiff,Enrico
50 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classification
description BACKGROUND: Physicochemical properties are frequently analyzed to characterize protein-sequences of known and unknown function. Especially the hydrophobicity of amino acids is often used for structural prediction or for the detection of membrane associated or embedded β-sheets and α-helices. For this purpose many scales classifying amino acids according to their physicochemical properties have been defined over the past decades. In parallel, several hydrophobicity parameters have been defined for calculation of peptide properties. We analyzed the performance of separating sequence pools using 98 hydrophobicity scales and five different hydrophobicity parameters, namely the overall hydrophobicity, the hydrophobic moment for detection of the α-helical and β-sheet membrane segments, the alternating hydrophobicity and the exact β-strand score. RESULTS: Most of the scales are capable of discriminating between transmembrane α-helices and transmembrane β-sheets, but assignment of peptides to pools of soluble peptides of different secondary structures is not achieved at the same quality. The separation capacity as measure of the discrimination between different structural elements is best by using the five different hydrophobicity parameters, but addition of the alternating hydrophobicity does not provide a large benefit. An in silico evolutionary approach shows that scales have limitation in separation capacity with a maximal threshold of 0.6 in general. We observed that scales derived from the evolutionary approach performed best in separating the different peptide pools when values for arginine and tyrosine were largely distinct from the value of glutamate. Finally, the separation of secondary structure pools via hydrophobicity can be supported by specific detectable patterns of four amino acids. CONCLUSION: It could be assumed that the quality of separation capacity of a certain scale depends on the spacing of the hydrophobicity value of certain amino acids. Irrespective of the wealth of hydrophobicity scales a scale separating all different kinds of secondary structures or between soluble and transmembrane peptides does not exist reflecting that properties other than hydrophobicity affect secondary structure formation as well. Nevertheless, application of hydrophobicity scales allows distinguishing between peptides with transmembrane α-helices and β-sheets. Furthermore, the overall separation capacity score of 0.6 using different hydrophobicity parameters could be assisted by pattern search on the protein sequence level for specific peptides with a length of four amino acids.
author Simm,Stefan
Einloft,Jens
Mirus,Oliver
Schleiff,Enrico
author_facet Simm,Stefan
Einloft,Jens
Mirus,Oliver
Schleiff,Enrico
author_sort Simm,Stefan
title 50 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classification
title_short 50 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classification
title_full 50 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classification
title_fullStr 50 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classification
title_full_unstemmed 50 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classification
title_sort 50 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classification
publisher Sociedad de Biología de Chile
publishDate 2016
url http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602016000100031
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AT mirusoliver 50yearsofaminoacidhydrophobicityscalesrevisitingthecapacityforpeptideclassification
AT schleiffenrico 50yearsofaminoacidhydrophobicityscalesrevisitingthecapacityforpeptideclassification
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