First evidence for accumulation of protein-bound and protein-free pyrraline in human uremic plasma by mass spectrometry.

Glucose-derived advanced glycation end products (AGEs) cross-link proteins and cause various biological tissue damage. One of them, pyrraline [epsilon-2-(formyl-5-hydroxymethyl-pyrrol-1-yl) -L-norleucine], has been demonstrated by utilizing antibody to accumulate in plasma and sclerosed matrix of diabetic individuals, suggesting responsibility for diabetic complications. To elucidate the involvement of pyrraline in uremia, we examined the pyrraline levels in patients with chronic renal failure by a mass spectrometric approach. Here we show that protein-free pyrraline as well as pyrraline with binding protein are significantly increased in non-diabetic uremic plasma compared to healthy subjects. Our results suggest that circulating pyrraline could be a substance contributing to complications in uremia.