LENS PROTEASOME SHOWS ENHANCED RATES OF DEGRADATION OF HYDROXYL RADICAL MODIFIED ALPHA-CRYSTALLIN

被引：66

作者：

MURAKAMI, K ^{[1
]}

JAHNGEN, JH ^{[1
]}

LIN, SW ^{[1
]}

DAVIES, KJA ^{[1
]}

TAYLOR, A ^{[1
]}

机构：

[1] TUFTS UNIV,USDA,HUMAN NUTR RES CTR,NUTR & CATARACT RES LAB,711 WASHINGTON ST,BOSTON,MA 02111

来源：

FREE RADICAL BIOLOGY AND MEDICINE | 1990年 / 8卷 / 03期

关键词：

Aging; Alpha-crystallin; Eye; High molecular weight protease; Irradiation; Lens; Macroxyproteinase (M.O.P.); Oxidation; Oxidative stress; Proteolysis;

D O I：

10.1016/0891-5849(90)90066-R

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Proteasome, a high molecular weight protease complex (HMP, ≈600 kDa) was isolated from bovine eye lens epithelium tissue. In contrast with prior reports, lens proteasome degraded the major lens protein alpha-crystallin and S-carboxymethylated bovine serum albumin at 37°C, mostly to trichloroacetic acid precipitable polypeptides. The proteasome, thus isolated, was labile at 55°C. As indicated by the ability of p-chloromercuribenzoate and N-ethylmaleimide to block activity, a thiol group is required for activity. Alpha-crystallin was oxidized by exposure to 60Co-irradiation under an atmosphere of N2O (1-50 kilorads). This dose delivered 0.1-5.7 mol of hydroxyl radicals per mol of crystallin. Irradiation resulted in increased heterogeneity, aggregation, and fragmentation of the crystallin preparation. The proteolytic susceptibility of alpha-crystallin to the lens HMP was enhanced by the irradiation in a dose-dependent manner up to 20 kilorads (.OH concentration up to 2.3 mol per mol of alpha-crystallin). When 50 kilorads (5.7 mol .OH per mol of alpha-crystallin) was used, there was extensive aggregation and no enhancement in proteolysis over the unirradiated sample. The data indicate that the lens HMP can degrade mildly photooxidized lens proteins, but proteins which are extensively damaged are not degraded and may accumulate. This may be related to cataract formation. © 1990.

引用

页码：217 / 222

页数：6

共 30 条

[1]

Thomson, Hum, Augusteyn, Reconstructing normal alpha-crystallin from the modified cataractous protein, Aust. J. Exp. Biol. Med. Sci., 63, pp. 563-571, (1985)

[2]

Harding, Crabbe, The lens: development, proteins, metabolism and cataract, The eye, 1 B, pp. 207-492, (1984)

[3]

Taylor, Davies, Protein oxidation and loss of protease activity may lead to cataract formation in the aged lens, Free Rad. Biol. Med., 3, pp. 371-377, (1987)

[4]

Ray, Harris, Purification of neutral lens endopeptidase: close similarity to a neutral proteinase in pituitary, Proc. Natl. Acad. Sci. USA, 82, pp. 7545-7549, (1985)

[5]

Ray, Harris, Comparative studies on lens neutral endopeptidase and pituitary neutral proteinase: two closely similar enzymes, FEBS Letts., 194, pp. 91-95, (1986)

[6]

Blow, van Heyningen, Barrett, Metal-dependent proteinase of the lens-assay, purification, and properties of the bovine enzyme, Biochem. J., 145, pp. 591-599, (1975)

[7]

Wilk, Orlowski, Cation-sensitive neutral endopeptidase: isolation and specificity of the bovine pituitary enzymes, J. Neurochem., 35, pp. 1172-1182, (1980)

[8]

Dahlmann, Keuhn, Rutschmann, Reinauer, Purification and characterization of a multicatalytic high-molecular-mass proteinase from rat skeletal muscle, Biochem. J., 228, pp. 161-170, (1985)

[9]

Mcguire, DeMartino, Purification and characterization of a high molecular weight proteinase (macropain) from human erythrocytes, Arch. Biochem. Biophys., 262, pp. 273-275, (1986)

[10]

Falkenburg, Haas, Kloetzel, Niedel, Kopp, Kuehn, Dahlmann, Drosophila small cytoplasmic 19S ribonucleoprotein is homologous to the rat multicatalytic protease, Nature, 331, pp. 190-192, (1987)

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