The amino acid sequence of the A chain of human α‐crystallin

Jong, Wilfried W. de; Terwindt, Eugénie C.; Bloemendal, H.

doi:10.1016/0014-5793(75)80286-9

Cited by 66 publications

(31 citation statements)

References 13 publications

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“…This conclusion is based upon isolation and characterization of peptides isolated from tryptic digests of the 10,000-dalton polypeptide. Excellent correspondence in residues 12-70 was found between the reported primary sequence of the human ca-crystallin A-chain (20) and the 10,000-dalton component. In the soluble fraction, the 10,000-dalton component remained relatively constant (>30 yr; 7%) with aging, whereas there was a continual decrease (0.29%/yr) in the 20,000-dalton soluble component (16).…”

Section: Resultsmentioning

confidence: 73%

Racemization in human lens: evidence of rapid insolubilization of specific polypeptides in cataract formation.

Garner¹,

Spector²

1978

Proc. Natl. Acad. Sci. U.S.A.

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After early life, the dry weight of normal human lenses increases at a relatively constant rate with time.Transformation from soluble to insoluble material appears to occur at a comparable rate, resulting in a constant amount of soluble material. However, in cataract the insolubilization rate is accelerated. These observations are supported by determination of D-aspartic acid/L-aspartic acid ratios. The lens is composed primarily of protein which comprises most of the dry weight (7). It has been previously shown that the relative percentage of water-insoluble material increases with aging in both animal (8) and human (9-11) lenses and in the development of lens opacities (9)(10)(11) (14).The subunit polypeptides of 65-to 72-year-old cataractous lens protein were isolated from Sephadex G-150 and G-100 equilibrated with 10% HOAc and 7.2 M urea as described elsewhere (15). All polypeptides described were reduced and alkylated prior to their purification unless otherwise noted. RESULTS AND DISCUSSIONWhen the total dry weight (water-soluble plus water-insoluble) of normal lenses is plotted against age, after the first few years of rapid growth an increase in apparent weight of approximately 0.4 mg/yr is found (Fig. 1). Similar results have been observed by Klethi (17). Determination of the dry weight of the water-insoluble fraction suggests that it increases at the same rate as the total dry weight. Such observations indicate that the absolute amount of the water-soluble fraction remains constant at approximately 30 mg, and the rate of conversion of soluble to insoluble material is constant in the normal lens. Thus, the percentage of insoluble material increases at a constant rate from about 2% at birth to approximately 50% by about age 70 years.When individual cataractous lenses were examined (open circles in Fig. 1), the total weight generally corresponded (within experimental error) to that of normal lenses of the same age group. However, the amount of the water-insoluble fraction in the cataractous lenses (solid circles) was dramtically greater than in the normal lenses, suggesting a more rapid conversion of soluble to insoluble material. Thus, it would appear that a relatively rapid loss of water-soluble protein may be correlated with lens opacity.The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.

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Section: Resultsmentioning

confidence: 73%

Racemization in human lens: evidence of rapid insolubilization of specific polypeptides in cataract formation.

Garner¹,

Spector²

1978

Proc. Natl. Acad. Sci. U.S.A.

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“…Therefore, the tightness of packing and the constraint placed on its movement may make crystallin less available for nonenzymatic glycation. A third factor that lowers the rate of nonenzymatic glycation of crystallins is the fact that the lysine content of alpha, beta, and gamma crystallins is lower than that of either human Hb or HSA (19,(44)(45)(46)(47)(48)(49). Gamma crystallin contains 1.2% lysine (two lysine residues per 165 total amino acids) (47), the a crystallin A and B chains have 4.1 and 5.7% lysine (44,45), and the crystallin (3-chain has 6.4% lysine (46).…”

Section: Discussionmentioning

confidence: 99%

“…The sites of nonenzymatic glycation of crystallin chains are not yet known. However, the B subunit of a crystallin has one Lys-Lys pair at the -COOH terminus (45), while the acrystallin A chain lacks a Lys-Lys pair (44). While the human beta and gamma crystallin chains have not been sequenced, the bovine gamma chain lacks a Lys-Lys pair (47), while the bovine beta chain has one Lys-Lys pair near the middle of the molecule (46).…”

Section: Discussionmentioning

confidence: 99%

Nonenzymatic glycation of human lens crystallin. Effect of aging and diabetes mellitus.

Garlick¹,

Mazer²,

Chylack³

et al. 1984

J. Clin. Invest.

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Abstract. We have examined the nonenzymatic glycation' of human lens crystallin, an extremely long-lived protein, from 16 normal human ocular lenses 0.2-99 yr of age, and from 11 diabetic lenses 52-82-yrold. The glucitol-lysine (Glc-Lys)2 content of soluble and insoluble crystallin was determined after reduction with 3H-borohydride followed by acid hydrolysis, boronic acid affinity chromatography, and high pressure cation exchange chromatography. Normal lens crystallin, soluble and insoluble, had 0.028±0.011 nanomoles GlcLys per nanomole crystallin monomer. Soluble and insoluble crystallins had equivalent levels of glycation. The content of Glc-Lys in normal lens crystallin increased with age in a linear fashion. Thus, the nonenzymatic glycation of nondiabetic lens crystallin may be regarded as a biological clock. The diabetic lens crystallin samples (n = 11) had a higher content of Glc-Lys Receivedfor publication 9 April 1984.

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“…Although serine has been reported, on the basis of carboxypeptidase digestions, to be the COOH-terminal residue of human B chains [ 121, we have to conclude that human Bz, like bovine Bz , has COOH-terminal lysine. The fact that human B2 and bovine B2 chains differ in 3 out of 175 positions, whereas human and bovine A chains differ in 10 out of 173 positions [6], indicates that the rate of evolution of the a-crystallin B chain is at least as slow as that of the A chain [13]. The A and B chains show 57% homology [7] and supposedly fulfill comparable roles in the a-crystallin aggregate which they build up together.…”

Section: Resultsmentioning

confidence: 99%

“…To understand these processes, which may also be relevant to the formation of cataract, it is necessary to know the structures of the A and B chains. The primary structure of human cy-crystallin A chain has previously been determined [6]. This letter shows that the human Bz chain differs only in three positions from the already known bovine B2 chain [7], thus demonstrating that the B chain, like the homologous A chain, has a very slow rate of evolutionary change.…”

Section: Introductionmentioning

confidence: 99%

The primary structure of the B₂ chain of human α‐crystallin

Kramps¹,

Man²,

Jong³

1977

FEBS Letters

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The amino acid sequence of the A chain of human α‐crystallin

Cited by 66 publications

References 13 publications

Racemization in human lens: evidence of rapid insolubilization of specific polypeptides in cataract formation.

Racemization in human lens: evidence of rapid insolubilization of specific polypeptides in cataract formation.

Nonenzymatic glycation of human lens crystallin. Effect of aging and diabetes mellitus.

The primary structure of the B₂ chain of human α‐crystallin

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The amino acid sequence of the A chain of human α‐crystallin

Cited by 66 publications

References 13 publications

Racemization in human lens: evidence of rapid insolubilization of specific polypeptides in cataract formation.

Racemization in human lens: evidence of rapid insolubilization of specific polypeptides in cataract formation.

Nonenzymatic glycation of human lens crystallin. Effect of aging and diabetes mellitus.

The primary structure of the B2 chain of human α‐crystallin

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The primary structure of the B₂ chain of human α‐crystallin