title: Primary sequence contribution to the optical function of the eye lens.
abstract: The crystallins have relatively high refractive increments compared to other proteins. The Greek key motif in βγ-crystallins was compared with that in other proteins, using predictive analysis from a protein database, to see whether this may be related to the refractive increment. Crystallins with Greek keys motifs have significantly higher refractive increments and more salt bridges than other proteins with Greek key domains. Specific amino acid substitutions: lysine and glutamic acid residues are replaced by arginine and aspartic acid, respectively as refractive increment increases. These trends are also seen in S-crystallins suggesting that the primary sequence of crystallins may be specifically enriched with amino acids with appropriate values of refractive increment to meet optical requirements. Comparison of crystallins from five species: two aquatic and three terrestrial shows that the lysine/arginine correlation with refractive increment occurs in all species investigated. This may be linked with formation and maintenance of salt bridges.
authors.affiliation: Faculty of Science Engineering and Computing, Kingston University, Penhryn Road, Kingston-upon-Thames, KT1 2EE, UK.
authors.forename: K
authors.initials: K
authors.lastname: Mahendiran
authors.affiliation: Department of Bioengineering, Nice Sophia Antipolis University Engineering School, Templiers Campus, 06410 Biot, France.
authors.forename: C
authors.initials: C
authors.lastname: Elie
authors.affiliation: Faculty of Science Engineering and Computing, Kingston University, Penhryn Road, Kingston-upon-Thames, KT1 2EE, UK.
authors.forename: J-C
authors.initials: JC
authors.lastname: Nebel
authors.affiliation: Faculty of Science Engineering and Computing, Kingston University, Penhryn Road, Kingston-upon-Thames, KT1 2EE, UK.
authors.forename: A
authors.initials: A
authors.lastname: Ryan
authors.affiliation: Faculty of Science Engineering and Computing, Kingston University, Penhryn Road, Kingston-upon-Thames, KT1 2EE, UK.
authors.forename: B K
authors.initials: BK
authors.lastname: Pierscionek
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D003459:Crystallins / Q000737:chemistry* / Q000378:metabolism; D007908:Lens, Crystalline / Q000737:chemistry*; D051379:Mice; D008958:Models, Molecular; D011487:Protein Conformation; D051381:Rats; D012029:Refraction, Ocular / Q000502:physiology*; D012031:Refractometry
chemical_list: D003459:Crystallins