Age-related cysteine uptake as rate-limiting in glutathione synthesis and glutathione half-life in the cultured human lens.
The study included human lenses of ages ranging from newborn to 92 years. Protein-free reduced glutathione decreased 14-fold, whereas protein-free oxidized glutathione increased 2.6-fold with increasing age. L-Cyst(e)ine uptake g-1 lens of very old cultured lenses decreased 70% from that exhibited in newborn lenses, demonstrating a marked decline of L-cyst(e)ine uptake as a function of age. In these same lenses the synthesis of reduced glutathione (mumol g-1 lens) decreased 73% with age. It was concluded that the glutathione decrease observed in the aging human lens was associated with decreased uptake of L-cyst(e)ine, decreased glutathione synthesis and possibly an increase in protein-free oxidized glutathione. The high correlation of L-cyst(e)ine uptake and glutathione synthesis supports the hypothesis that L-cyst(e)ine uptake is a rate-limiting factor of glutathione synthesis in the intact human lens. By the use of buthionine sulfoximine, the half-life of glutathione was estimated to be 90 hr in the cultured human lens.
Rathbun
W B
WB
Ophthalmology Department, University of Minnesota, Minneapolis 55455.
Murray
D L
DL
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism; D019328:Buthionine Sulfoximine; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000378:metabolism*; D005978:Glutathione / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D006207:Half-Life; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007908:Lens, Crystalline / Q000378:metabolism*; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology; D008875:Middle Aged
D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D005978:Glutathione; D003545:Cysteine