Age-related Changes in Human Lens Crystallins Identified by Two-dimensional Electrophoresis and Mass Spectrometry

• Published in: Experimental eye research 1998-07, Vol.67 (1), p.31-43
• Main Authors: LAMPI, KIRSTEN J., MA, ZHIXIANG, HANSON, STACY R.A., AZUMA, MISUYOSHI, SHIH, MARJORIE, SHEARER, THOMAS R., SMITH, DAVID L., SMITH, JEAN B., DAVID, LARRY L.
• Format: Article
• Language: English
• Subjects: Adolescent; aging; Aging - metabolism; Biological and medical sciences; Cataract - metabolism; Child, Preschool; crystallins; Crystallins - chemistry; deamidation; Electrophoresis, Gel, Two-Dimensional; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; human; Humans; Infant; lens; Lens, Crystalline - chemistry; Lens, Crystalline - embryology; Mass Spectrometry; Middle Aged; proteolysis; two-dimensional electrophoresis; Vertebrates: nervous system and sense organs
• ISSN: 0014-4835; 1096-0007
• DOI: 10.1006/exer.1998.0481

The purpose of this study was to identify the major protein components in adult human lenses and to analyse the specific age-related changes in these proteins using two-dimensional electrophoresis, Edman sequencing, and in conjunction with the data in the accompanying manuscript, mass spectrometry. The majority of changes in the two-dimensional electrophoretic pattern of lens proteins occurred prior to 17 years of age, and included a decrease in proteins migrating to the original positions of βB1, βB3, βA3, γC and γD, and the appearance of many new species with apparent molecular weights on two-dimensional electrophoretic gels similar to βB2 and γS, but having more acidic pIs. These proteins were identified as deamidated forms of βB1 and βA3/A1 missing portions of theirN-terminal extensions. With the exception of αB, deamidation was detected in all crystallin species. These data indicated that a major fraction of the water-soluble protein of the adult human lens is composed of truncated βB1 and βA3/A1 crystallins, and that nearly all human crystallins, including the β-crystallins, are susceptible to deamidation. The results also provided the most detailed map to date of the identities of protein species on two-dimensional electrophoresis gels of adult human lenses.