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Biomedical subjects

A Spector

Publications and source records attributed to A Spector.

At least 163 records · Page 9Linked to original sources
PubMed1976

Absence of low-molecular-weight alpha crystallin in nuclear region of old human lenses.

Examination of old human lenses indicates that low-molecular-weight alpha crystallin is not present in the inner 30-40%, the nucleus, of the lens. The remainder of such lenses, the periphery, contains normal levels of this protein. This finding is in marked contrast to observations in young lenses, where a large quantity of this protein is found throughout the tissue.

Aging↗
PubMed1976

Human alpha-crystallin. I. The isolation and characterization of newly synthesized alpha-crystallin.

Studies of the incorporation of 14C amino acids into human lens proteins demonstrate that an alpha-crystallin fraction takes up more than six times as much radioactivity as any other lens protein. Based on analyses with a calibrated Bio-Gel A-1.5 m column, a molecular weight of 4.9 x 10(5) +/- 5 per cent was obtained for this protein while sedimentation equilibrium analyses indicated a weight average molecular weight, Mw, of 7.5 x 10(5) +/- 4 per cent at 10,000 r.p.m. Gel electrophoresis in sodium dodecyl sulfate revealed two components with molecular weights of 22,000 and 20,000, values similar to those found with calf alpha-crystallin. Alkaline urea gel electrophoresis indicated one major polypeptide with a mobility similar to the B2 chain of calf alpha-crystallin and two major bands with mobilities between those of the calf alpha-crystallin A2 and A1 chains. Amino acid analyses of this newly synthesized alpha-crystallin gave a composition which with a few exceptions is very similar to that of calf alpha-crystallin. All three major polypeptides contained 14C amino acids. However, from the present data, it cannot be determined whether the three polypeptides were independently synthesized or a rapid transformation produced one of the labeled polypeptides in the A region. There appears to be between three and four times as many presumptive A as B polypeptides.

Amino Acids↗
PubMed1976

Human alpha-crystallin-III isolation and characterization of protein from normal infant lenses and old lens peripheries.

Alpha-crystallin isolated from the peripheries of old normal or cataractous lenses appears to be identical, consisting of eleven polypeptides, five B, and six A chains. In contrast, alpha-crystallin isolated from normal six-week-old human lenses has only three major polypeptides, corresponding to B1, A1, and A2 of the old human lens protein as well as small amounts of some of the other components. Comparisons with bovine alpha-crystallin are also reported. Based on gel filtration experiments with Bio-Gel A-1.5m, two distinct populations of alpha-crystallin were found in old lens periphery, one containing species greater than 1.5 X 10(6) daltons and another of approximately 9 X 10(5) daltons. In the cataract preparations, the higher molecular weight fraction is predominant. This fraction is not present in young lenses.

Aged↗