Article

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

Departments of Oral Molecular Biology and Ophthalmology, Oregon Health Sciences University, Portland, Oregon, 97201; Department of Chemistry, University of Nebraska, Lincoln, Nebraska, 68588; Senju Pharmaceutical Co. Ltd. Kobe, 651 22, Japan
Experimental Eye Research (impact factor: 3.26). 08/1998; DOI:10.1006/exer.1998.0481 pp.31-43

ABSTRACT 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.

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Keywords

acidic pIs
 
apparent molecular weights
 
deamidated forms
 
detailed map
 
human crystallins
 
lens proteins
 
major fraction
 
major protein components
 
original positions
 
protein species
 
proteins
 
proteins migrating
 
specific age-related changes
 
two-dimensional electrophoresis
 
two-dimensional electrophoresis gels
 
two-dimensional electrophoretic gels
 
two-dimensional electrophoretic pattern
 
water-soluble protein
 
β-crystallins
 
βA3/A1 crystallins