Structural studies on bovine γ-crystallin

Abstract

The amino acid sequences around the cysteine residues in the lens protein, gamma-crystallin, were studied. Fraction II of the gamma-crystallin from calf lens (Björk, 1964) was used. The protein was oxidized with performic acid and then hydrolysed with trypsin. Six peptides containing cysteic acid were isolated. One of the peptides contained three residues of cysteic acid and the others contained one residue of cysteic acid. We conclude that there are eight unique residues of cysteic acid in the oxidized protein. Amino acid analysis suggests that there are also eight residues of cysteic acid in the molecule, which thus contains only one polypeptide chain.

Microheterogeneity at the C-terminus of γ-crystallin fraction IVb

“…Val-Met-Asp-Phe-Tyr In view of the organogenesis of the lens (Pirie & van Heyningen, 1956) it is noteworthy that y-crystallin fraction IVb, which is heterogeneous, is more abundant in the nuclear region of the lens (Bjork, 1961), and is comprised of the early foetal proteins, whereas fraction II, which is homogeneous (Croft, 1972), is more concentrated, relative to fraction IVb, in the cortex of the lens, which develops later.…”

“…Materials and methods y-Crystallin fraction IVb was prepared from calf lenses by gel filtration on Sephadex G-75, followed by ion-exchange chromatography on sulphopropyl-Sephadex (Bjork, 1961(Bjork, , 1964. Phospho-cellulose was obtained from Brown Co., Berlin, N.H., U.S.A. All other materials and methods were as described by Croft & Waley (1971) and Croft (1971). Amino acid analyses were performed on a Locarte amino acid analyser, with a single column for the determination of acidic, neutral and basic amino acids.…”

Isolation of a zinc protein from the tapetum lucidum of the cat

“…The moisture content was determined after drying to constant weight in an evacuated drying 'pistol' at 120°C. The isolated material was oxidized with performic acid as described by Croft & Waley (1971). The oxidized protein was digested with trypsin and subjected to peptide 'mapping' as described by Croft (1971).…”

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

“…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. Other materials were as described by Croft & Waley (1971).…”

“…(a) Performic acidoxidized y-crystallin. The protein was oxidized with performic acid as described by Croft & Waley (1971). (b) S-Carboxymethyl y-crystallin.…”