The amino-acid sequence of gamma crystallin

Abstract

The amino-acid sequence of gamma crystallin, fraction 11, has been determined, which indicates it to be a single chain polypeptide of 165 amino-acid residues.THE y-crystallins are a group of cryoproteins present in the vertebrate lens. Four homogeneous proteins (fractions 11, IIIa, b, and IVb) were isolated and crystallized from calf lens by Bjork.1-3 Recently, interest has been centred on these proteins as it has been suggested that they may be involved in cataract formation. 4 This communication describes the determination of the amino-acid sequence of fraction 11, which is the first lens protein to have its aminoacid sequence described.The protein used in this study was prepared from calf lenses by the method of Bjork.1$2 Amino-acid analysis indicated the following composition in molar ratios : Lys (2),

Spectroscopic investigations of bovine lens crystallins. 1. Circular dichroism and intrinsic fluorescence

“…The primary structure of the lens crystalline has been investigated in detail (Harding & Dilley, 1976), but very little is known about their three-dimensional-structure, the interactions between different segments of the specific chains of amino acids, and the orientation of specific reactive amino acids and groups susceptible to chemical change. Although some circular dichroism (CD) studies (Croft, 1972;Li, 1974;Li & Spector, 1974;Horwitz, 1976;Horwitz et al, 1977;Zigler et al, 1980) have been reported, systematic studies and detailed analyses are lacking.…”

The amino acid sequence of γ-crystallin (fraction II) from calf lens

“…In the present paper I give evidence for the amino acid sequence of y-crystallin (fraction II) from calf lens. A preliminary report of this work has been published (Croft, 1972). Experimental Materials y-Crystallin (fraction II) was prepared from calf lenses by the method of Bjork (1961Bjork ( , 1964, the only modifications being that the buffers used were 10mM with respect to ,B-mercaptoethanol and the final chromatography on phosphocellulose was omitted.…”

Changes of Lens Crystallins Photosensitized with Tryptophan Metabolites

“…It seems that insol ubilization of crystallins depends on the amount of cysteine in the molecule of each crystallin. It was reported that the contents of cysteine were 0.5% in a-crystallin [Spector et al, 1971], 1.7% in pH-crystallin, 0.9% in pL-crystallin [Herbrink and Bloemendal, 1974] and 3.7% in y-crystallin [Croft, 1972], It is known that the high molecular weight insoluble protein associated by disulfide bond increases during aging or cataractogenesis of the human lenses [Harding, 1973;Spector and Roy, 1978]. It is suggested that this insoluble protein could arise from P-and y-crystallins.…”

“…a-and (3-crystallins were then dialyzed ex haustively against water, lyophilized and dissolved in 0.1 M potassium phosphate buffer, pH 7.0 (3 mg protcin/ml). It is known that y-crystallin contains much cysteine (3.7%) [Croft, 1972], compared with other crystallins, so y-crystallin (0.46 mg/ml) was used with out dialysis and lyophilization to prevent its oxida tion during preparation.…”